From 93c1800b3799f17375989b0daf76497dd3e80922 Mon Sep 17 00:00:00 2001 From: David Kaplan Date: Sun, 2 Jun 2024 13:19:09 -0500 Subject: [PATCH 1/2] x86/kexec: Fix bug with call depth tracking The call to cc_platform_has() triggers a fault and system crash if call depth tracking is active because the GS segment has been reset by load_segments() and GS_BASE is now 0 but call depth tracking uses per-CPU variables to operate. Call cc_platform_has() earlier in the function when GS is still valid. [ bp: Massage. ] Fixes: 5d8213864ade ("x86/retbleed: Add SKL return thunk") Signed-off-by: David Kaplan Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Tom Lendacky Cc: Link: https://lore.kernel.org/r/20240603083036.637-1-bp@kernel.org --- arch/x86/kernel/machine_kexec_64.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c index b180d8e497c3..cc0f7f70b17b 100644 --- a/arch/x86/kernel/machine_kexec_64.c +++ b/arch/x86/kernel/machine_kexec_64.c @@ -295,8 +295,15 @@ void machine_kexec_cleanup(struct kimage *image) void machine_kexec(struct kimage *image) { unsigned long page_list[PAGES_NR]; - void *control_page; + unsigned int host_mem_enc_active; int save_ftrace_enabled; + void *control_page; + + /* + * This must be done before load_segments() since if call depth tracking + * is used then GS must be valid to make any function calls. + */ + host_mem_enc_active = cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT); #ifdef CONFIG_KEXEC_JUMP if (image->preserve_context) @@ -358,7 +365,7 @@ void machine_kexec(struct kimage *image) (unsigned long)page_list, image->start, image->preserve_context, - cc_platform_has(CC_ATTR_HOST_MEM_ENCRYPT)); + host_mem_enc_active); #ifdef CONFIG_KEXEC_JUMP if (image->preserve_context) From c625dabbf1c4a8e77e4734014f2fde7aa9071a1f Mon Sep 17 00:00:00 2001 From: Yazen Ghannam Date: Mon, 3 Apr 2023 16:42:44 +0000 Subject: [PATCH 2/2] x86/amd_nb: Check for invalid SMN reads AMD Zen-based systems use a System Management Network (SMN) that provides access to implementation-specific registers. SMN accesses are done indirectly through an index/data pair in PCI config space. The PCI config access may fail and return an error code. This would prevent the "read" value from being updated. However, the PCI config access may succeed, but the return value may be invalid. This is in similar fashion to PCI bad reads, i.e. return all bits set. Most systems will return 0 for SMN addresses that are not accessible. This is in line with AMD convention that unavailable registers are Read-as-Zero/Writes-Ignored. However, some systems will return a "PCI Error Response" instead. This value, along with an error code of 0 from the PCI config access, will confuse callers of the amd_smn_read() function. Check for this condition, clear the return value, and set a proper error code. Fixes: ddfe43cdc0da ("x86/amd_nb: Add SMN and Indirect Data Fabric access for AMD Fam17h") Signed-off-by: Yazen Ghannam Signed-off-by: Borislav Petkov (AMD) Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20230403164244.471141-1-yazen.ghannam@amd.com --- arch/x86/kernel/amd_nb.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/arch/x86/kernel/amd_nb.c b/arch/x86/kernel/amd_nb.c index 3cf156f70859..027a8c7a2c9e 100644 --- a/arch/x86/kernel/amd_nb.c +++ b/arch/x86/kernel/amd_nb.c @@ -215,7 +215,14 @@ out: int amd_smn_read(u16 node, u32 address, u32 *value) { - return __amd_smn_rw(node, address, value, false); + int err = __amd_smn_rw(node, address, value, false); + + if (PCI_POSSIBLE_ERROR(*value)) { + err = -ENODEV; + *value = 0; + } + + return err; } EXPORT_SYMBOL_GPL(amd_smn_read);