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linux-next/arch/x86
Vitaly Kuznetsov b6162e82ae KVM: nSVM: Preserve registers modifications done before nested_svm_vmexit()
L2 guest hang is observed after 'exit_required' was dropped and nSVM
switched to check_nested_events() completely. The hang is a busy loop when
e.g. KVM is emulating an instruction (e.g. L2 is accessing MMIO space and
we drop to userspace). After nested_svm_vmexit() and when L1 is doing VMRUN
nested guest's RIP is not advanced so KVM goes into emulating the same
instruction which caused nested_svm_vmexit() and the loop continues.

nested_svm_vmexit() is not new, however, with check_nested_events() we're
now calling it later than before. In case by that time KVM has modified
register state we may pick stale values from VMCB when trying to save
nested guest state to nested VMCB.

nVMX code handles this case correctly: sync_vmcs02_to_vmcs12() called from
nested_vmx_vmexit() does e.g 'vmcs12->guest_rip = kvm_rip_read(vcpu)' and
this ensures KVM-made modifications are preserved. Do the same for nSVM.

Generally, nested_vmx_vmexit()/nested_svm_vmexit() need to pick up all
nested guest state modifications done by KVM after vmexit. It would be
great to find a way to express this in a way which would not require to
manually track these changes, e.g. nested_{vmcb,vmcs}_get_field().

Co-debugged-with: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Message-Id: <20200527090102.220647-1-vkuznets@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2020-05-27 13:11:12 -04:00
..
boot SPDX patches for 5.7-rc1. 2020-04-03 13:12:26 -07:00
configs compiler: remove CONFIG_OPTIMIZE_INLINING entirely 2020-04-07 10:43:42 -07:00
crypto crypto: arch/nhpoly1305 - process in explicit 4k chunks 2020-04-30 15:16:59 +10:00
entry x86/kvm: Handle async page faults directly through do_page_fault() 2020-05-19 15:53:57 +02:00
events perf/x86/cstate: Add Jasper Lake CPU support 2020-04-22 21:43:12 +02:00
hyperv x86/hyperv: Suspend/resume the VP assist page for hibernation 2020-04-21 10:03:19 +01:00
ia32 Merge branch 'x86-cleanups-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2020-03-31 11:04:05 -07:00
include KVM: x86: Take an unsigned 32-bit int for has_emulated_msr()'s index 2020-05-27 13:11:08 -04:00
kernel x86/kvm: Restrict ASYNC_PF to user space 2020-05-19 15:53:58 +02:00
kvm KVM: nSVM: Preserve registers modifications done before nested_svm_vmexit() 2020-05-27 13:11:12 -04:00
lib SPDX patches for 5.7-rc1. 2020-04-03 13:12:26 -07:00
math-emu Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-11-26 10:42:40 -08:00
mm x86/kvm: Handle async page faults directly through do_page_fault() 2020-05-19 15:53:57 +02:00
net bpf, x86_32: Fix logic error in BPF_LDX zero-extension 2020-04-24 17:23:01 -07:00
oprofile x86: Use pr_warn instead of pr_warning 2019-10-18 15:00:18 +02:00
pci pci-v5.6-changes 2020-01-31 14:48:54 -08:00
platform efi/x86: Don't remap text<->rodata gap read-only for mixed mode 2020-04-14 08:32:17 +02:00
power x86/kernel: Convert to new CPU match macros 2020-03-24 21:28:26 +01:00
purgatory Merge branch 'x86-asm-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-11-26 10:42:40 -08:00
ras
realmode SPDX patches for 5.7-rc1. 2020-04-03 13:12:26 -07:00
tools .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
um mm/vma: define a default value for VM_DATA_DEFAULT_FLAGS 2020-04-10 15:36:21 -07:00
video
xen xen: branch for v5.7-rc1b 2020-04-10 17:20:06 -07:00
.gitignore .gitignore: add SPDX License Identifier 2020-03-25 11:50:48 +01:00
Kbuild
Kconfig mm/userfaultfd: disable userfaultfd-wp on x86_32 2020-04-21 11:11:55 -07:00
Kconfig.assembler x86: update AS_* macros to binutils >=2.23, supporting ADX and AVX2 2020-04-09 00:12:48 +09:00
Kconfig.cpu x86/cpu: Detect VMX features on Intel, Centaur and Zhaoxin CPUs 2020-01-13 18:02:53 +01:00
Kconfig.debug x86: mm: convert dump_pagetables to use walk_page_range 2020-02-04 03:05:25 +00:00
Makefile x86: probe assembler capabilities via kconfig instead of makefile 2020-04-09 00:01:59 +09:00
Makefile_32.cpu x86/math-emu: Limit MATH_EMULATION to 486SX compatibles 2019-10-03 10:51:17 +02:00
Makefile.um