This is a note to let you know that I've just added the patch titled
x86/cpufeatures: Add CPUID_LNX_5 to track recently added Linux-defined word
to the 6.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
x86-cpufeatures-add-cpuid_lnx_5-to-track-recently-added-linux-defined-word.patch
and it can be found in the queue-6.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 8cb4a9a82b21623dbb4b3051dd30d98356cf95bc Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@xxxxxxxxxx>
Date: Thu, 4 Apr 2024 17:16:14 -0700
Subject: x86/cpufeatures: Add CPUID_LNX_5 to track recently added Linux-defined word
From: Sean Christopherson <seanjc@xxxxxxxxxx>
commit 8cb4a9a82b21623dbb4b3051dd30d98356cf95bc upstream.
Add CPUID_LNX_5 to track cpufeatures' word 21, and add the appropriate
compile-time assert in KVM to prevent direct lookups on the features in
CPUID_LNX_5. KVM uses X86_FEATURE_* flags to manage guest CPUID, and so
must translate features that are scattered by Linux from the Linux-defined
bit to the hardware-defined bit, i.e. should never try to directly access
scattered features in guest CPUID.
Opportunistically add NR_CPUID_WORDS to enum cpuid_leafs, along with a
compile-time assert in KVM's CPUID infrastructure to ensure that future
additions update cpuid_leafs along with NCAPINTS.
No functional change intended.
Fixes: 7f274e609f3d ("x86/cpufeatures: Add new word for scattered features")
Cc: Sandipan Das <sandipan.das@xxxxxxx>
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/include/asm/cpufeature.h | 2 ++
arch/x86/kvm/reverse_cpuid.h | 2 ++
2 files changed, 4 insertions(+)
--- a/arch/x86/include/asm/cpufeature.h
+++ b/arch/x86/include/asm/cpufeature.h
@@ -33,6 +33,8 @@ enum cpuid_leafs
CPUID_7_EDX,
CPUID_8000_001F_EAX,
CPUID_8000_0021_EAX,
+ CPUID_LNX_5,
+ NR_CPUID_WORDS,
};
#define X86_CAP_FMT_NUM "%d:%d"
--- a/arch/x86/kvm/reverse_cpuid.h
+++ b/arch/x86/kvm/reverse_cpuid.h
@@ -102,10 +102,12 @@ static const struct cpuid_reg reverse_cp
*/
static __always_inline void reverse_cpuid_check(unsigned int x86_leaf)
{
+ BUILD_BUG_ON(NR_CPUID_WORDS != NCAPINTS);
BUILD_BUG_ON(x86_leaf == CPUID_LNX_1);
BUILD_BUG_ON(x86_leaf == CPUID_LNX_2);
BUILD_BUG_ON(x86_leaf == CPUID_LNX_3);
BUILD_BUG_ON(x86_leaf == CPUID_LNX_4);
+ BUILD_BUG_ON(x86_leaf == CPUID_LNX_5);
BUILD_BUG_ON(x86_leaf >= ARRAY_SIZE(reverse_cpuid));
BUILD_BUG_ON(reverse_cpuid[x86_leaf].function == 0);
}
Patches currently in stable-queue which might be from seanjc@xxxxxxxxxx are
queue-6.8/x86-cpufeatures-add-cpuid_lnx_5-to-track-recently-added-linux-defined-word.patch
