From 063452fd94d153d4eb38ad58f210f3d37a09cca4 Mon Sep 17 00:00:00 2001 From: Yang Zhong Date: Sat, 29 Jan 2022 09:36:46 -0800 Subject: [PATCH 01/12] x86/fpu/xstate: Fix the ARCH_REQ_XCOMP_PERM implementation ARCH_REQ_XCOMP_PERM is supposed to add the requested feature to the permission bitmap of thread_group_leader()->fpu. But the code overwrites the bitmap with the requested feature bit only rather than adding it. Fix the code to add the requested feature bit to the master bitmask. Fixes: db8268df0983 ("x86/arch_prctl: Add controls for dynamic XSTATE components") Signed-off-by: Yang Zhong Signed-off-by: Chang S. Bae Signed-off-by: Thomas Gleixner Cc: Paolo Bonzini Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20220129173647.27981-2-chang.seok.bae@intel.com --- arch/x86/kernel/fpu/xstate.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 7c7824ae7862..dc6d5e98d296 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -1639,7 +1639,7 @@ static int __xstate_request_perm(u64 permitted, u64 requested, bool guest) perm = guest ? &fpu->guest_perm : &fpu->perm; /* Pairs with the READ_ONCE() in xstate_get_group_perm() */ - WRITE_ONCE(perm->__state_perm, requested); + WRITE_ONCE(perm->__state_perm, mask); /* Protected by sighand lock */ perm->__state_size = ksize; perm->__user_state_size = usize; From 20df737561484cb2d42e537663c03a7311d2b3c1 Mon Sep 17 00:00:00 2001 From: "Chang S. Bae" Date: Sat, 29 Jan 2022 09:36:47 -0800 Subject: [PATCH 02/12] selftests/x86/amx: Update the ARCH_REQ_XCOMP_PERM test Update the arch_prctl test to check the permission bitmap whether the requested feature is added as expected or not. Every non-dynamic feature that is enabled is permitted already for use. TILECFG is not dynamic feature. Ensure the bit is always on from ARCH_GET_XCOMP_PERM. Signed-off-by: Chang S. Bae Signed-off-by: Thomas Gleixner Link: https://lore.kernel.org/r/20220129173647.27981-3-chang.seok.bae@intel.com --- tools/testing/selftests/x86/amx.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/x86/amx.c b/tools/testing/selftests/x86/amx.c index 3615ef4a48bb..2189f0322d8b 100644 --- a/tools/testing/selftests/x86/amx.c +++ b/tools/testing/selftests/x86/amx.c @@ -368,9 +368,16 @@ static void req_xtiledata_perm(void) static void validate_req_xcomp_perm(enum expected_result exp) { - unsigned long bitmask; + unsigned long bitmask, expected_bitmask; long rc; + rc = syscall(SYS_arch_prctl, ARCH_GET_XCOMP_PERM, &bitmask); + if (rc) { + fatal_error("prctl(ARCH_GET_XCOMP_PERM) error: %ld", rc); + } else if (!(bitmask & XFEATURE_MASK_XTILECFG)) { + fatal_error("ARCH_GET_XCOMP_PERM returns XFEATURE_XTILECFG off."); + } + rc = syscall(SYS_arch_prctl, ARCH_REQ_XCOMP_PERM, XFEATURE_XTILEDATA); if (exp == FAIL_EXPECTED) { if (rc) { @@ -383,10 +390,15 @@ static void validate_req_xcomp_perm(enum expected_result exp) fatal_error("ARCH_REQ_XCOMP_PERM saw unexpected failure.\n"); } + expected_bitmask = bitmask | XFEATURE_MASK_XTILEDATA; + rc = syscall(SYS_arch_prctl, ARCH_GET_XCOMP_PERM, &bitmask); if (rc) { fatal_error("prctl(ARCH_GET_XCOMP_PERM) error: %ld", rc); - } else if (bitmask & XFEATURE_MASK_XTILE) { + } else if (bitmask != expected_bitmask) { + fatal_error("ARCH_REQ_XCOMP_PERM set a wrong bitmask: %lx, expected: %lx.\n", + bitmask, expected_bitmask); + } else { printf("\tARCH_REQ_XCOMP_PERM is successful.\n"); } } From b9080ba4a6ec56447f263082825a4fddb873316b Mon Sep 17 00:00:00 2001 From: Borislav Petkov Date: Wed, 23 Mar 2022 12:21:10 +0100 Subject: [PATCH 03/12] x86/defconfig: Enable WERROR To quote Linus: "EVERYBODY should have CONFIG_WERROR=y on at least x86-64 and other serious architectures, unless you have some completely random experimental (and broken) compiler. New compiler warnings are not acceptable." So this should make at least the most obvious and common ones not go unnoticed. Acked-by: Linus Torvalds Signed-off-by: Borislav Petkov Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/YjsCpoRK7W4l6tSh@zn.tnic --- arch/x86/configs/i386_defconfig | 1 + arch/x86/configs/x86_64_defconfig | 1 + 2 files changed, 2 insertions(+) diff --git a/arch/x86/configs/i386_defconfig b/arch/x86/configs/i386_defconfig index 71124cf8630c..4b2085243aa3 100644 --- a/arch/x86/configs/i386_defconfig +++ b/arch/x86/configs/i386_defconfig @@ -262,3 +262,4 @@ CONFIG_PROVIDE_OHCI1394_DMA_INIT=y CONFIG_EARLY_PRINTK_DBGP=y CONFIG_DEBUG_BOOT_PARAMS=y CONFIG_KALLSYMS_ALL=y +CONFIG_WERROR=y diff --git a/arch/x86/configs/x86_64_defconfig b/arch/x86/configs/x86_64_defconfig index 92b1169ec90b..38c52e4eb30b 100644 --- a/arch/x86/configs/x86_64_defconfig +++ b/arch/x86/configs/x86_64_defconfig @@ -258,3 +258,4 @@ CONFIG_PROVIDE_OHCI1394_DMA_INIT=y CONFIG_EARLY_PRINTK_DBGP=y CONFIG_DEBUG_BOOT_PARAMS=y CONFIG_KALLSYMS_ALL=y +CONFIG_WERROR=y From 410ce3dd5055b3fa68fb7f99a6756be3a7e17f22 Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Thu, 24 Mar 2022 09:31:13 +0100 Subject: [PATCH 04/12] x86/config: Make the x86 defconfigs a bit more usable - Use 'make savedefconfig' to refresh & regenerate the files - Add in KVM boot enablers - Enable the cgroup features most distros rely on [ fix bug found by Nathan Chancellor ] Acked-by: Nathan Chancellor Cc: Linus Torvalds Cc: Borislav Petkov Cc: Thomas Gleixner Cc: Peter Zijlstra Signed-off-by: Ingo Molnar Link: https://lore.kernel.org/r/YjwsUT/6PkRPjnHE@gmail.com --- arch/x86/configs/i386_defconfig | 51 +++++++++++++++++++++---------- arch/x86/configs/x86_64_defconfig | 38 +++++++++++++++++------ 2 files changed, 63 insertions(+), 26 deletions(-) diff --git a/arch/x86/configs/i386_defconfig b/arch/x86/configs/i386_defconfig index 4b2085243aa3..98a4852ed6a0 100644 --- a/arch/x86/configs/i386_defconfig +++ b/arch/x86/configs/i386_defconfig @@ -1,5 +1,7 @@ +CONFIG_WERROR=y CONFIG_SYSVIPC=y CONFIG_POSIX_MQUEUE=y +CONFIG_USELIB=y CONFIG_AUDIT=y CONFIG_NO_HZ=y CONFIG_HIGH_RES_TIMERS=y @@ -11,23 +13,30 @@ CONFIG_TASK_XACCT=y CONFIG_TASK_IO_ACCOUNTING=y CONFIG_LOG_BUF_SHIFT=18 CONFIG_CGROUPS=y +CONFIG_BLK_CGROUP=y CONFIG_CGROUP_SCHED=y +CONFIG_CGROUP_PIDS=y +CONFIG_CGROUP_RDMA=y CONFIG_CGROUP_FREEZER=y +CONFIG_CGROUP_HUGETLB=y CONFIG_CPUSETS=y +CONFIG_CGROUP_DEVICE=y CONFIG_CGROUP_CPUACCT=y +CONFIG_CGROUP_PERF=y +CONFIG_CGROUP_MISC=y +CONFIG_CGROUP_DEBUG=y CONFIG_BLK_DEV_INITRD=y +CONFIG_KALLSYMS_ALL=y # CONFIG_COMPAT_BRK is not set CONFIG_PROFILING=y -# CONFIG_64BIT is not set CONFIG_SMP=y -CONFIG_X86_GENERIC=y -CONFIG_HPET_TIMER=y +CONFIG_HYPERVISOR_GUEST=y +CONFIG_PARAVIRT=y +CONFIG_NR_CPUS=8 CONFIG_X86_REROUTE_FOR_BROKEN_BOOT_IRQS=y -CONFIG_X86_REBOOTFIXUPS=y CONFIG_MICROCODE_AMD=y CONFIG_X86_MSR=y CONFIG_X86_CPUID=y -CONFIG_HIGHPTE=y CONFIG_X86_CHECK_BIOS_CORRUPTION=y # CONFIG_MTRR_SANITIZER is not set CONFIG_EFI=y @@ -43,12 +52,15 @@ CONFIG_ACPI_BGRT=y CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE=y CONFIG_CPU_FREQ_GOV_ONDEMAND=y CONFIG_X86_ACPI_CPUFREQ=y -CONFIG_EFI_VARS=y CONFIG_KPROBES=y CONFIG_JUMP_LABEL=y +CONFIG_COMPAT_32BIT_TIME=y CONFIG_MODULES=y CONFIG_MODULE_UNLOAD=y CONFIG_MODULE_FORCE_UNLOAD=y +CONFIG_BLK_CGROUP_IOLATENCY=y +CONFIG_BLK_CGROUP_IOCOST=y +CONFIG_BLK_CGROUP_IOPRIO=y CONFIG_BINFMT_MISC=y CONFIG_NET=y CONFIG_PACKET=y @@ -103,12 +115,16 @@ CONFIG_IP6_NF_FILTER=y CONFIG_IP6_NF_TARGET_REJECT=y CONFIG_IP6_NF_MANGLE=y CONFIG_NET_SCHED=y +CONFIG_NET_CLS_CGROUP=y CONFIG_NET_EMATCH=y CONFIG_NET_CLS_ACT=y +CONFIG_CGROUP_NET_PRIO=y CONFIG_CFG80211=y CONFIG_MAC80211=y CONFIG_MAC80211_LEDS=y CONFIG_RFKILL=y +CONFIG_NET_9P=y +CONFIG_NET_9P_VIRTIO=y CONFIG_PCI=y CONFIG_PCIEPORTBUS=y CONFIG_PCI_MSI=y @@ -119,13 +135,16 @@ CONFIG_DEVTMPFS=y CONFIG_DEVTMPFS_MOUNT=y CONFIG_DEBUG_DEVRES=y CONFIG_CONNECTOR=y +CONFIG_EFI_VARS=y +CONFIG_EFI_CAPSULE_LOADER=y CONFIG_BLK_DEV_LOOP=y +CONFIG_VIRTIO_BLK=y CONFIG_BLK_DEV_SD=y CONFIG_BLK_DEV_SR=y CONFIG_CHR_DEV_SG=y CONFIG_SCSI_CONSTANTS=y CONFIG_SCSI_SPI_ATTRS=y -# CONFIG_SCSI_LOWLEVEL is not set +CONFIG_SCSI_VIRTIO=y CONFIG_ATA=y CONFIG_SATA_AHCI=y CONFIG_ATA_PIIX=y @@ -143,6 +162,7 @@ CONFIG_MACINTOSH_DRIVERS=y CONFIG_MAC_EMUMOUSEBTN=y CONFIG_NETDEVICES=y CONFIG_NETCONSOLE=y +CONFIG_VIRTIO_NET=y CONFIG_BNX2=y CONFIG_TIGON3=y CONFIG_NET_TULIP=y @@ -170,6 +190,7 @@ CONFIG_SERIAL_8250_SHARE_IRQ=y CONFIG_SERIAL_8250_DETECT_IRQ=y CONFIG_SERIAL_8250_RSA=y CONFIG_SERIAL_NONSTANDARD=y +CONFIG_VIRTIO_CONSOLE=y CONFIG_HW_RANDOM=y CONFIG_NVRAM=y CONFIG_HPET=y @@ -181,12 +202,7 @@ CONFIG_AGP_AMD64=y CONFIG_AGP_INTEL=y CONFIG_DRM=y CONFIG_DRM_I915=y -CONFIG_FB_MODE_HELPERS=y -CONFIG_FB_TILEBLITTING=y -CONFIG_FB_EFI=y -CONFIG_LOGO=y -# CONFIG_LOGO_LINUX_MONO is not set -# CONFIG_LOGO_LINUX_VGA16 is not set +CONFIG_DRM_VIRTIO_GPU=y CONFIG_SOUND=y CONFIG_SND=y CONFIG_SND_HRTIMER=y @@ -219,6 +235,8 @@ CONFIG_USB_STORAGE=y CONFIG_RTC_CLASS=y # CONFIG_RTC_HCTOSYS is not set CONFIG_DMADEVICES=y +CONFIG_VIRTIO_PCI=y +CONFIG_VIRTIO_INPUT=y CONFIG_EEEPC_LAPTOP=y CONFIG_EXT4_FS=y CONFIG_EXT4_FS_POSIX_ACL=y @@ -240,6 +258,7 @@ CONFIG_NFS_FS=y CONFIG_NFS_V3_ACL=y CONFIG_NFS_V4=y CONFIG_ROOT_NFS=y +CONFIG_9P_FS=y CONFIG_NLS_DEFAULT="utf8" CONFIG_NLS_CODEPAGE_437=y CONFIG_NLS_ASCII=y @@ -251,15 +270,15 @@ CONFIG_SECURITY_SELINUX=y CONFIG_SECURITY_SELINUX_BOOTPARAM=y CONFIG_SECURITY_SELINUX_DISABLE=y CONFIG_PRINTK_TIME=y +CONFIG_FRAME_WARN=1024 CONFIG_MAGIC_SYSRQ=y CONFIG_DEBUG_KERNEL=y CONFIG_DEBUG_STACK_USAGE=y -CONFIG_DEBUG_STACKOVERFLOW=y # CONFIG_SCHED_DEBUG is not set CONFIG_SCHEDSTATS=y CONFIG_BLK_DEV_IO_TRACE=y CONFIG_PROVIDE_OHCI1394_DMA_INIT=y CONFIG_EARLY_PRINTK_DBGP=y CONFIG_DEBUG_BOOT_PARAMS=y -CONFIG_KALLSYMS_ALL=y -CONFIG_WERROR=y +CONFIG_UNWINDER_FRAME_POINTER=y +# CONFIG_64BIT is not set diff --git a/arch/x86/configs/x86_64_defconfig b/arch/x86/configs/x86_64_defconfig index 38c52e4eb30b..69784505a7a8 100644 --- a/arch/x86/configs/x86_64_defconfig +++ b/arch/x86/configs/x86_64_defconfig @@ -1,3 +1,4 @@ +CONFIG_WERROR=y CONFIG_SYSVIPC=y CONFIG_POSIX_MQUEUE=y CONFIG_AUDIT=y @@ -11,14 +12,25 @@ CONFIG_TASK_XACCT=y CONFIG_TASK_IO_ACCOUNTING=y CONFIG_LOG_BUF_SHIFT=18 CONFIG_CGROUPS=y +CONFIG_BLK_CGROUP=y CONFIG_CGROUP_SCHED=y +CONFIG_CGROUP_PIDS=y +CONFIG_CGROUP_RDMA=y CONFIG_CGROUP_FREEZER=y +CONFIG_CGROUP_HUGETLB=y CONFIG_CPUSETS=y +CONFIG_CGROUP_DEVICE=y CONFIG_CGROUP_CPUACCT=y +CONFIG_CGROUP_PERF=y +CONFIG_CGROUP_MISC=y +CONFIG_CGROUP_DEBUG=y CONFIG_BLK_DEV_INITRD=y +CONFIG_KALLSYMS_ALL=y # CONFIG_COMPAT_BRK is not set CONFIG_PROFILING=y CONFIG_SMP=y +CONFIG_HYPERVISOR_GUEST=y +CONFIG_PARAVIRT=y CONFIG_X86_REROUTE_FOR_BROKEN_BOOT_IRQS=y CONFIG_MICROCODE_AMD=y CONFIG_X86_MSR=y @@ -41,12 +53,14 @@ CONFIG_CPU_FREQ_DEFAULT_GOV_USERSPACE=y CONFIG_CPU_FREQ_GOV_ONDEMAND=y CONFIG_X86_ACPI_CPUFREQ=y CONFIG_IA32_EMULATION=y -CONFIG_EFI_VARS=y CONFIG_KPROBES=y CONFIG_JUMP_LABEL=y CONFIG_MODULES=y CONFIG_MODULE_UNLOAD=y CONFIG_MODULE_FORCE_UNLOAD=y +CONFIG_BLK_CGROUP_IOLATENCY=y +CONFIG_BLK_CGROUP_IOCOST=y +CONFIG_BLK_CGROUP_IOPRIO=y CONFIG_BINFMT_MISC=y CONFIG_NET=y CONFIG_PACKET=y @@ -101,12 +115,16 @@ CONFIG_IP6_NF_FILTER=y CONFIG_IP6_NF_TARGET_REJECT=y CONFIG_IP6_NF_MANGLE=y CONFIG_NET_SCHED=y +CONFIG_NET_CLS_CGROUP=y CONFIG_NET_EMATCH=y CONFIG_NET_CLS_ACT=y +CONFIG_CGROUP_NET_PRIO=y CONFIG_CFG80211=y CONFIG_MAC80211=y CONFIG_MAC80211_LEDS=y CONFIG_RFKILL=y +CONFIG_NET_9P=y +CONFIG_NET_9P_VIRTIO=y CONFIG_PCI=y CONFIG_PCIEPORTBUS=y CONFIG_HOTPLUG_PCI=y @@ -116,13 +134,15 @@ CONFIG_DEVTMPFS=y CONFIG_DEVTMPFS_MOUNT=y CONFIG_DEBUG_DEVRES=y CONFIG_CONNECTOR=y +CONFIG_EFI_VARS=y CONFIG_BLK_DEV_LOOP=y +CONFIG_VIRTIO_BLK=y CONFIG_BLK_DEV_SD=y CONFIG_BLK_DEV_SR=y CONFIG_CHR_DEV_SG=y CONFIG_SCSI_CONSTANTS=y CONFIG_SCSI_SPI_ATTRS=y -# CONFIG_SCSI_LOWLEVEL is not set +CONFIG_SCSI_VIRTIO=y CONFIG_ATA=y CONFIG_SATA_AHCI=y CONFIG_ATA_PIIX=y @@ -138,6 +158,7 @@ CONFIG_MACINTOSH_DRIVERS=y CONFIG_MAC_EMUMOUSEBTN=y CONFIG_NETDEVICES=y CONFIG_NETCONSOLE=y +CONFIG_VIRTIO_NET=y CONFIG_TIGON3=y CONFIG_NET_TULIP=y CONFIG_E100=y @@ -162,6 +183,7 @@ CONFIG_SERIAL_8250_SHARE_IRQ=y CONFIG_SERIAL_8250_DETECT_IRQ=y CONFIG_SERIAL_8250_RSA=y CONFIG_SERIAL_NONSTANDARD=y +CONFIG_VIRTIO_CONSOLE=y CONFIG_HW_RANDOM=y # CONFIG_HW_RANDOM_INTEL is not set # CONFIG_HW_RANDOM_AMD is not set @@ -175,12 +197,7 @@ CONFIG_AGP_AMD64=y CONFIG_AGP_INTEL=y CONFIG_DRM=y CONFIG_DRM_I915=y -CONFIG_FB_MODE_HELPERS=y -CONFIG_FB_TILEBLITTING=y -CONFIG_FB_EFI=y -CONFIG_LOGO=y -# CONFIG_LOGO_LINUX_MONO is not set -# CONFIG_LOGO_LINUX_VGA16 is not set +CONFIG_DRM_VIRTIO_GPU=y CONFIG_SOUND=y CONFIG_SND=y CONFIG_SND_HRTIMER=y @@ -213,6 +230,8 @@ CONFIG_USB_STORAGE=y CONFIG_RTC_CLASS=y # CONFIG_RTC_HCTOSYS is not set CONFIG_DMADEVICES=y +CONFIG_VIRTIO_PCI=y +CONFIG_VIRTIO_INPUT=y CONFIG_EEEPC_LAPTOP=y CONFIG_AMD_IOMMU=y CONFIG_INTEL_IOMMU=y @@ -237,6 +256,7 @@ CONFIG_NFS_FS=y CONFIG_NFS_V3_ACL=y CONFIG_NFS_V4=y CONFIG_ROOT_NFS=y +CONFIG_9P_FS=y CONFIG_NLS_DEFAULT="utf8" CONFIG_NLS_CODEPAGE_437=y CONFIG_NLS_ASCII=y @@ -257,5 +277,3 @@ CONFIG_BLK_DEV_IO_TRACE=y CONFIG_PROVIDE_OHCI1394_DMA_INIT=y CONFIG_EARLY_PRINTK_DBGP=y CONFIG_DEBUG_BOOT_PARAMS=y -CONFIG_KALLSYMS_ALL=y -CONFIG_WERROR=y From 4009a4ac82dd95b8cd2b62bd30019476983f0aff Mon Sep 17 00:00:00 2001 From: Joerg Roedel Date: Mon, 21 Mar 2022 10:33:51 +0100 Subject: [PATCH 05/12] x86/sev: Unroll string mmio with CC_ATTR_GUEST_UNROLL_STRING_IO The io-specific memcpy/memset functions use string mmio accesses to do their work. Under SEV, the hypervisor can't emulate these instructions because they read/write directly from/to encrypted memory. KVM will inject a page fault exception into the guest when it is asked to emulate string mmio instructions for an SEV guest: BUG: unable to handle page fault for address: ffffc90000065068 #PF: supervisor read access in kernel mode #PF: error_code(0x0000) - not-present page PGD 8000100000067 P4D 8000100000067 PUD 80001000fb067 PMD 80001000fc067 PTE 80000000fed40173 Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.17.0-rc7 #3 As string mmio for an SEV guest can not be supported by the hypervisor, unroll the instructions for CC_ATTR_GUEST_UNROLL_STRING_IO enabled kernels. This issue appears when kernels are launched in recent libvirt-managed SEV virtual machines, because virt-install started to add a tpm-crb device to the guest by default and proactively because, raisins: https://github.com/virt-manager/virt-manager/commit/eb58c09f488b0633ed1eea012cd311e48864401e and as that commit says, the default adding of a TPM can be disabled with "virt-install ... --tpm none". The kernel driver for tpm-crb uses memcpy_to/from_io() functions to access MMIO memory, resulting in a page-fault injected by KVM and crashing the kernel at boot. [ bp: Massage and extend commit message. ] Fixes: d8aa7eea78a1 ('x86/mm: Add Secure Encrypted Virtualization (SEV) support') Signed-off-by: Joerg Roedel Signed-off-by: Borislav Petkov Reviewed-by: Tom Lendacky Cc: Link: https://lore.kernel.org/r/20220321093351.23976-1-joro@8bytes.org --- arch/x86/lib/iomem.c | 65 ++++++++++++++++++++++++++++++++++++++------ 1 file changed, 57 insertions(+), 8 deletions(-) diff --git a/arch/x86/lib/iomem.c b/arch/x86/lib/iomem.c index df50451d94ef..3e2f33fc33de 100644 --- a/arch/x86/lib/iomem.c +++ b/arch/x86/lib/iomem.c @@ -22,7 +22,7 @@ static __always_inline void rep_movs(void *to, const void *from, size_t n) : "memory"); } -void memcpy_fromio(void *to, const volatile void __iomem *from, size_t n) +static void string_memcpy_fromio(void *to, const volatile void __iomem *from, size_t n) { if (unlikely(!n)) return; @@ -38,9 +38,8 @@ void memcpy_fromio(void *to, const volatile void __iomem *from, size_t n) } rep_movs(to, (const void *)from, n); } -EXPORT_SYMBOL(memcpy_fromio); -void memcpy_toio(volatile void __iomem *to, const void *from, size_t n) +static void string_memcpy_toio(volatile void __iomem *to, const void *from, size_t n) { if (unlikely(!n)) return; @@ -56,14 +55,64 @@ void memcpy_toio(volatile void __iomem *to, const void *from, size_t n) } rep_movs((void *)to, (const void *) from, n); } + +static void unrolled_memcpy_fromio(void *to, const volatile void __iomem *from, size_t n) +{ + const volatile char __iomem *in = from; + char *out = to; + int i; + + for (i = 0; i < n; ++i) + out[i] = readb(&in[i]); +} + +static void unrolled_memcpy_toio(volatile void __iomem *to, const void *from, size_t n) +{ + volatile char __iomem *out = to; + const char *in = from; + int i; + + for (i = 0; i < n; ++i) + writeb(in[i], &out[i]); +} + +static void unrolled_memset_io(volatile void __iomem *a, int b, size_t c) +{ + volatile char __iomem *mem = a; + int i; + + for (i = 0; i < c; ++i) + writeb(b, &mem[i]); +} + +void memcpy_fromio(void *to, const volatile void __iomem *from, size_t n) +{ + if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO)) + unrolled_memcpy_fromio(to, from, n); + else + string_memcpy_fromio(to, from, n); +} +EXPORT_SYMBOL(memcpy_fromio); + +void memcpy_toio(volatile void __iomem *to, const void *from, size_t n) +{ + if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO)) + unrolled_memcpy_toio(to, from, n); + else + string_memcpy_toio(to, from, n); +} EXPORT_SYMBOL(memcpy_toio); void memset_io(volatile void __iomem *a, int b, size_t c) { - /* - * TODO: memset can mangle the IO patterns quite a bit. - * perhaps it would be better to use a dumb one: - */ - memset((void *)a, b, c); + if (cc_platform_has(CC_ATTR_GUEST_UNROLL_STRING_IO)) { + unrolled_memset_io(a, b, c); + } else { + /* + * TODO: memset can mangle the IO patterns quite a bit. + * perhaps it would be better to use a dumb one: + */ + memset((void *)a, b, c); + } } EXPORT_SYMBOL(memset_io); From a9f84fb7158fea60cbcadef5c0166fb22b469091 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 24 Mar 2022 14:47:08 +0100 Subject: [PATCH 06/12] x86/fpu: Remove redundant XCOMP_BV initialization fpu_copy_uabi_to_guest_fpstate() initializes the XCOMP_BV field in the XSAVE header. That's a leftover from the old KVM FPU buffer handling code. Since d69c1382e1b7 ("x86/kvm: Convert FPU handling to a single swap buffer") KVM uses the FPU core allocation code, which initializes the XCOMP_BV field already. Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/20220324134623.408932232@linutronix.de --- arch/x86/kernel/fpu/core.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/arch/x86/kernel/fpu/core.c b/arch/x86/kernel/fpu/core.c index 19821f027cb3..c049561f373a 100644 --- a/arch/x86/kernel/fpu/core.c +++ b/arch/x86/kernel/fpu/core.c @@ -415,9 +415,6 @@ int fpu_copy_uabi_to_guest_fpstate(struct fpu_guest *gfpu, const void *buf, xpkru = get_xsave_addr(&kstate->regs.xsave, XFEATURE_PKRU); *vpkru = xpkru->pkru; } - - /* Ensure that XCOMP_BV is set up for XSAVES */ - xstate_init_xcomp_bv(&kstate->regs.xsave, kstate->xfeatures); return 0; } EXPORT_SYMBOL_GPL(fpu_copy_uabi_to_guest_fpstate); From d47f71f6de7970d504748d1a60a11c51af5bce47 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 24 Mar 2022 14:47:09 +0100 Subject: [PATCH 07/12] x86/fpu: Remove unused supervisor only offsets No users. Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/20220324134623.465066249@linutronix.de --- arch/x86/kernel/fpu/xstate.c | 30 ------------------------------ 1 file changed, 30 deletions(-) diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index dc6d5e98d296..dc33556779f7 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -83,8 +83,6 @@ static unsigned int xstate_sizes[XFEATURE_MAX] __ro_after_init = { [ 0 ... XFEATURE_MAX - 1] = -1}; static unsigned int xstate_comp_offsets[XFEATURE_MAX] __ro_after_init = { [ 0 ... XFEATURE_MAX - 1] = -1}; -static unsigned int xstate_supervisor_only_offsets[XFEATURE_MAX] __ro_after_init = - { [ 0 ... XFEATURE_MAX - 1] = -1}; /* * Return whether the system supports a given xfeature. @@ -324,33 +322,6 @@ static void __init setup_xstate_comp_offsets(void) } } -/* - * Setup offsets of a supervisor-state-only XSAVES buffer: - * - * The offsets stored in xstate_comp_offsets[] only work for one specific - * value of the Requested Feature BitMap (RFBM). In cases where a different - * RFBM value is used, a different set of offsets is required. This set of - * offsets is for when RFBM=xfeatures_mask_supervisor(). - */ -static void __init setup_supervisor_only_offsets(void) -{ - unsigned int next_offset; - int i; - - next_offset = FXSAVE_SIZE + XSAVE_HDR_SIZE; - - for_each_extended_xfeature(i, fpu_kernel_cfg.max_features) { - if (!xfeature_is_supervisor(i)) - continue; - - if (xfeature_is_aligned(i)) - next_offset = ALIGN(next_offset, 64); - - xstate_supervisor_only_offsets[i] = next_offset; - next_offset += xstate_sizes[i]; - } -} - /* * Print out xstate component offsets and sizes */ @@ -951,7 +922,6 @@ void __init fpu__init_system_xstate(unsigned int legacy_size) setup_init_fpu_buf(); setup_xstate_comp_offsets(); - setup_supervisor_only_offsets(); /* * Paranoia check whether something in the setup modified the From 35a77d4503d9d9d0e19e3a2a0d3fc9ab09fb6857 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 24 Mar 2022 14:47:11 +0100 Subject: [PATCH 08/12] x86/fpu/xsave: Initialize offset/size cache early Reading XSTATE feature information from CPUID over and over does not make sense. The information has to be cached anyway, so it can be done early. Prepare for runtime calculation of XSTATE offsets and allow consolidation of the size calculation functions in a later step. Rename the function while at it as it does not setup any features. Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/20220324134623.519411939@linutronix.de --- arch/x86/kernel/fpu/xstate.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index dc33556779f7..814c2fddbd83 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -180,7 +180,7 @@ static bool xfeature_enabled(enum xfeature xfeature) * Record the offsets and sizes of various xstates contained * in the XSAVE state memory layout. */ -static void __init setup_xstate_features(void) +static void __init setup_xstate_cache(void) { u32 eax, ebx, ecx, edx, i; /* start at the beginning of the "extended state" */ @@ -390,7 +390,6 @@ static void __init setup_init_fpu_buf(void) if (!boot_cpu_has(X86_FEATURE_XSAVE)) return; - setup_xstate_features(); print_xstate_features(); xstate_init_xcomp_bv(&init_fpstate.regs.xsave, fpu_kernel_cfg.max_features); @@ -906,6 +905,10 @@ void __init fpu__init_system_xstate(unsigned int legacy_size) /* Enable xstate instructions to be able to continue with initialization: */ fpu__init_cpu_xstate(); + + /* Cache size, offset and flags for initialization */ + setup_xstate_cache(); + err = init_xstate_size(); if (err) goto out_disable; From 6afbb58cc2251c1d83472ca3005638206e73b6b8 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 24 Mar 2022 14:47:12 +0100 Subject: [PATCH 09/12] x86/fpu: Cache xfeature flags from CPUID In preparation for runtime calculation of XSAVE offsets cache the feature flags for each XSTATE component during feature enumeration via CPUID(0xD). EDX has two relevant bits: 0 Supervisor component 1 Feature storage must be 64 byte aligned These bits are currently only evaluated during init, but the alignment bit must be cached to make runtime calculation of XSAVE offsets efficient. Cache the full EDX content and use it for the existing alignment and supervisor checks. Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/20220324134623.573656209@linutronix.de --- arch/x86/kernel/fpu/xstate.c | 49 ++++++++++-------------------------- 1 file changed, 13 insertions(+), 36 deletions(-) diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 814c2fddbd83..5a069c2a3675 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -83,6 +83,10 @@ static unsigned int xstate_sizes[XFEATURE_MAX] __ro_after_init = { [ 0 ... XFEATURE_MAX - 1] = -1}; static unsigned int xstate_comp_offsets[XFEATURE_MAX] __ro_after_init = { [ 0 ... XFEATURE_MAX - 1] = -1}; +static unsigned int xstate_flags[XFEATURE_MAX] __ro_after_init; + +#define XSTATE_FLAG_SUPERVISOR BIT(0) +#define XSTATE_FLAG_ALIGNED64 BIT(1) /* * Return whether the system supports a given xfeature. @@ -122,17 +126,14 @@ int cpu_has_xfeatures(u64 xfeatures_needed, const char **feature_name) } EXPORT_SYMBOL_GPL(cpu_has_xfeatures); +static bool xfeature_is_aligned64(int xfeature_nr) +{ + return xstate_flags[xfeature_nr] & XSTATE_FLAG_ALIGNED64; +} + static bool xfeature_is_supervisor(int xfeature_nr) { - /* - * Extended State Enumeration Sub-leaves (EAX = 0DH, ECX = n, n > 1) - * returns ECX[0] set to (1) for a supervisor state, and cleared (0) - * for a user state. - */ - u32 eax, ebx, ecx, edx; - - cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx); - return ecx & 1; + return xstate_flags[xfeature_nr] & XSTATE_FLAG_SUPERVISOR; } /* @@ -203,6 +204,7 @@ static void __init setup_xstate_cache(void) cpuid_count(XSTATE_CPUID, i, &eax, &ebx, &ecx, &edx); xstate_sizes[i] = eax; + xstate_flags[i] = ecx; /* * If an xfeature is supervisor state, the offset in EBX is @@ -261,31 +263,6 @@ static void __init print_xstate_features(void) WARN_ON(nr >= XFEATURE_MAX); \ } while (0) -/* - * We could cache this like xstate_size[], but we only use - * it here, so it would be a waste of space. - */ -static int xfeature_is_aligned(int xfeature_nr) -{ - u32 eax, ebx, ecx, edx; - - CHECK_XFEATURE(xfeature_nr); - - if (!xfeature_enabled(xfeature_nr)) { - WARN_ONCE(1, "Checking alignment of disabled xfeature %d\n", - xfeature_nr); - return 0; - } - - cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx); - /* - * The value returned by ECX[1] indicates the alignment - * of state component 'i' when the compacted format - * of the extended region of an XSAVE area is used: - */ - return !!(ecx & 2); -} - /* * This function sets up offsets and sizes of all extended states in * xsave area. This supports both standard format and compacted format @@ -314,7 +291,7 @@ static void __init setup_xstate_comp_offsets(void) next_offset = FXSAVE_SIZE + XSAVE_HDR_SIZE; for_each_extended_xfeature(i, fpu_kernel_cfg.max_features) { - if (xfeature_is_aligned(i)) + if (xfeature_is_aligned64(i)) next_offset = ALIGN(next_offset, 64); xstate_comp_offsets[i] = next_offset; @@ -619,7 +596,7 @@ static unsigned int xstate_calculate_size(u64 xfeatures, bool compacted) for_each_extended_xfeature(i, xfeatures) { /* Align from the end of the previous feature */ - if (xfeature_is_aligned(i)) + if (xfeature_is_aligned64(i)) size = ALIGN(size, 64); /* * In compacted format the enabled features are packed, From 7aa5128b5fea26cf224766303ea3b8df343f9a87 Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 24 Mar 2022 14:47:13 +0100 Subject: [PATCH 10/12] x86/fpu/xsave: Handle compacted offsets correctly with supervisor states So far the cached fixed compacted offsets worked, but with (re-)enabling of ENQCMD this does no longer work with KVM fpstate. KVM does not have supervisor features enabled for the guest FPU, which means that KVM has then a different XSAVE area layout than the host FPU state. This in turn breaks the copy from/to UABI functions when invoked for a guest state. Remove the pre-calculated compacted offsets and calculate the offset of each component at runtime based on the XCOMP_BV field in the XSAVE header. The runtime overhead is not interesting because these copy from/to UABI functions are not used in critical fast paths. KVM uses them to save and restore FPU state during migration. The host uses them for ptrace and for the slow path of 32bit signal handling. Fixes: 7c1ef59145f1 ("x86/cpufeatures: Re-enable ENQCMD") Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/20220324134623.627636809@linutronix.de --- arch/x86/kernel/fpu/xstate.c | 86 +++++++++++++++++------------------- 1 file changed, 41 insertions(+), 45 deletions(-) diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 5a069c2a3675..c55f72eb5466 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -81,8 +81,6 @@ static unsigned int xstate_offsets[XFEATURE_MAX] __ro_after_init = { [ 0 ... XFEATURE_MAX - 1] = -1}; static unsigned int xstate_sizes[XFEATURE_MAX] __ro_after_init = { [ 0 ... XFEATURE_MAX - 1] = -1}; -static unsigned int xstate_comp_offsets[XFEATURE_MAX] __ro_after_init = - { [ 0 ... XFEATURE_MAX - 1] = -1}; static unsigned int xstate_flags[XFEATURE_MAX] __ro_after_init; #define XSTATE_FLAG_SUPERVISOR BIT(0) @@ -136,6 +134,33 @@ static bool xfeature_is_supervisor(int xfeature_nr) return xstate_flags[xfeature_nr] & XSTATE_FLAG_SUPERVISOR; } +static unsigned int xfeature_get_offset(u64 xcomp_bv, int xfeature) +{ + unsigned int offs, i; + + /* + * Non-compacted format and legacy features use the cached fixed + * offsets. + */ + if (!cpu_feature_enabled(X86_FEATURE_XSAVES) || xfeature <= XFEATURE_SSE) + return xstate_offsets[xfeature]; + + /* + * Compacted format offsets depend on the actual content of the + * compacted xsave area which is determined by the xcomp_bv header + * field. + */ + offs = FXSAVE_SIZE + XSAVE_HDR_SIZE; + for_each_extended_xfeature(i, xcomp_bv) { + if (xfeature_is_aligned64(i)) + offs = ALIGN(offs, 64); + if (i == xfeature) + break; + offs += xstate_sizes[i]; + } + return offs; +} + /* * Enable the extended processor state save/restore feature. * Called once per CPU onlining. @@ -263,42 +288,6 @@ static void __init print_xstate_features(void) WARN_ON(nr >= XFEATURE_MAX); \ } while (0) -/* - * This function sets up offsets and sizes of all extended states in - * xsave area. This supports both standard format and compacted format - * of the xsave area. - */ -static void __init setup_xstate_comp_offsets(void) -{ - unsigned int next_offset; - int i; - - /* - * The FP xstates and SSE xstates are legacy states. They are always - * in the fixed offsets in the xsave area in either compacted form - * or standard form. - */ - xstate_comp_offsets[XFEATURE_FP] = 0; - xstate_comp_offsets[XFEATURE_SSE] = offsetof(struct fxregs_state, - xmm_space); - - if (!cpu_feature_enabled(X86_FEATURE_XSAVES)) { - for_each_extended_xfeature(i, fpu_kernel_cfg.max_features) - xstate_comp_offsets[i] = xstate_offsets[i]; - return; - } - - next_offset = FXSAVE_SIZE + XSAVE_HDR_SIZE; - - for_each_extended_xfeature(i, fpu_kernel_cfg.max_features) { - if (xfeature_is_aligned64(i)) - next_offset = ALIGN(next_offset, 64); - - xstate_comp_offsets[i] = next_offset; - next_offset += xstate_sizes[i]; - } -} - /* * Print out xstate component offsets and sizes */ @@ -308,7 +297,8 @@ static void __init print_xstate_offset_size(void) for_each_extended_xfeature(i, fpu_kernel_cfg.max_features) { pr_info("x86/fpu: xstate_offset[%d]: %4d, xstate_sizes[%d]: %4d\n", - i, xstate_comp_offsets[i], i, xstate_sizes[i]); + i, xfeature_get_offset(fpu_kernel_cfg.max_features, i), + i, xstate_sizes[i]); } } @@ -901,7 +891,6 @@ void __init fpu__init_system_xstate(unsigned int legacy_size) fpu_user_cfg.max_features); setup_init_fpu_buf(); - setup_xstate_comp_offsets(); /* * Paranoia check whether something in the setup modified the @@ -956,13 +945,19 @@ void fpu__resume_cpu(void) */ static void *__raw_xsave_addr(struct xregs_state *xsave, int xfeature_nr) { - if (!xfeature_enabled(xfeature_nr)) { - WARN_ON_FPU(1); + u64 xcomp_bv = xsave->header.xcomp_bv; + + if (WARN_ON_ONCE(!xfeature_enabled(xfeature_nr))) return NULL; + + if (cpu_feature_enabled(X86_FEATURE_XSAVES)) { + if (WARN_ON_ONCE(!(xcomp_bv & BIT_ULL(xfeature_nr)))) + return NULL; } - return (void *)xsave + xstate_comp_offsets[xfeature_nr]; + return (void *)xsave + xfeature_get_offset(xcomp_bv, xfeature_nr); } + /* * Given the xsave area and a state inside, this function returns the * address of the state. @@ -993,8 +988,9 @@ void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr) * We should not ever be requesting features that we * have not enabled. */ - WARN_ONCE(!(fpu_kernel_cfg.max_features & BIT_ULL(xfeature_nr)), - "get of unsupported state"); + if (WARN_ON_ONCE(!xfeature_enabled(xfeature_nr))) + return NULL; + /* * This assumes the last 'xsave*' instruction to * have requested that 'xfeature_nr' be saved. From 781c64bfcb735960717d1cb45428047ff6a5030c Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Thu, 24 Mar 2022 14:47:14 +0100 Subject: [PATCH 11/12] x86/fpu/xstate: Handle supervisor states in XSTATE permissions The size calculation in __xstate_request_perm() fails to take supervisor states into account because the permission bitmap is only relevant for user states. Up to 5.17 this does not matter because there are no supervisor states supported, but the (re-)enabling of ENQCMD makes them available. Fixes: 7c1ef59145f1 ("x86/cpufeatures: Re-enable ENQCMD") Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/20220324134623.681768598@linutronix.de --- arch/x86/kernel/fpu/xstate.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index c55f72eb5466..5ac934b48d4a 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -1571,6 +1571,9 @@ static int __xstate_request_perm(u64 permitted, u64 requested, bool guest) /* Calculate the resulting kernel state size */ mask = permitted | requested; + /* Take supervisor states into account on the host */ + if (!guest) + mask |= xfeatures_mask_supervisor(); ksize = xstate_calculate_size(mask, compacted); /* Calculate the resulting user state size */ From d6d6d50f1e801a790a242c80eeda261e36c43b7b Mon Sep 17 00:00:00 2001 From: Thomas Gleixner Date: Mon, 28 Mar 2022 20:43:21 +0200 Subject: [PATCH 12/12] x86/fpu/xstate: Consolidate size calculations Use the offset calculation to do the size calculation which avoids yet another series of CPUID instructions for each invocation. [ Fix the FP/SSE only case which missed to take the xstate header into account, as Reported-by: kernel test robot ] Signed-off-by: Thomas Gleixner Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/87o81pgbp2.ffs@tglx --- arch/x86/kernel/fpu/xstate.c | 49 ++++++------------------------------ 1 file changed, 8 insertions(+), 41 deletions(-) diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c index 5ac934b48d4a..39e1c8626ab9 100644 --- a/arch/x86/kernel/fpu/xstate.c +++ b/arch/x86/kernel/fpu/xstate.c @@ -385,25 +385,6 @@ static void __init setup_init_fpu_buf(void) fxsave(&init_fpstate.regs.fxsave); } -static int xfeature_uncompacted_offset(int xfeature_nr) -{ - u32 eax, ebx, ecx, edx; - - /* - * Only XSAVES supports supervisor states and it uses compacted - * format. Checking a supervisor state's uncompacted offset is - * an error. - */ - if (XFEATURE_MASK_SUPERVISOR_ALL & BIT_ULL(xfeature_nr)) { - WARN_ONCE(1, "No fixed offset for xstate %d\n", xfeature_nr); - return -1; - } - - CHECK_XFEATURE(xfeature_nr); - cpuid_count(XSTATE_CPUID, xfeature_nr, &eax, &ebx, &ecx, &edx); - return ebx; -} - int xfeature_size(int xfeature_nr) { u32 eax, ebx, ecx, edx; @@ -581,29 +562,15 @@ static bool __init check_xstate_against_struct(int nr) static unsigned int xstate_calculate_size(u64 xfeatures, bool compacted) { - unsigned int size = FXSAVE_SIZE + XSAVE_HDR_SIZE; - int i; + unsigned int topmost = fls64(xfeatures) - 1; + unsigned int offset = xstate_offsets[topmost]; - for_each_extended_xfeature(i, xfeatures) { - /* Align from the end of the previous feature */ - if (xfeature_is_aligned64(i)) - size = ALIGN(size, 64); - /* - * In compacted format the enabled features are packed, - * i.e. disabled features do not occupy space. - * - * In non-compacted format the offsets are fixed and - * disabled states still occupy space in the memory buffer. - */ - if (!compacted) - size = xfeature_uncompacted_offset(i); - /* - * Add the feature size even for non-compacted format - * to make the end result correct - */ - size += xfeature_size(i); - } - return size; + if (topmost <= XFEATURE_SSE) + return sizeof(struct xregs_state); + + if (compacted) + offset = xfeature_get_offset(xfeatures, topmost); + return offset + xstate_sizes[topmost]; } /*