]> git.ipfire.org Git - thirdparty/kernel/stable.git/commit
KVM: x86: Use feature_bit() to clear CONSTANT_TSC when emulating CPUID
authorSean Christopherson <seanjc@google.com>
Thu, 28 Nov 2024 01:33:28 +0000 (17:33 -0800)
committerSean Christopherson <seanjc@google.com>
Wed, 18 Dec 2024 22:19:22 +0000 (14:19 -0800)
commitccf4c1d15d5a593bb3a50911ce3e8bb373feddc5
treecd34c6974945a1ea30bde1c1576a332b8b59360c
parent9af04539d474dda4984ff4909d4568e6123c8cba
KVM: x86: Use feature_bit() to clear CONSTANT_TSC when emulating CPUID

When clearing CONSTANT_TSC during CPUID emulation due to a Hyper-V quirk,
use feature_bit() instead of SF() to ensure the bit is actually cleared.
SF() evaluates to zero if the _host_ doesn't support the feature.  I.e.
KVM could keep the bit set if userspace advertised CONSTANT_TSC despite
it not being supported in hardware.

Note, translating from a scattered feature to a the hardware version is
done by __feature_translate(), not SF().  The sole purpose of SF() is to
check kernel support for the scattered feature, *before* translation.

Cc: Vitaly Kuznetsov <vkuznets@redhat.com>
Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>
Link: https://lore.kernel.org/r/20241128013424.4096668-2-seanjc@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
arch/x86/kvm/cpuid.c