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From: Aaron Lewis <aaronlewis@google.com>
To: jmattson@google.com, kvm@vger.kernel.org
Cc: Aaron Lewis <aaronlewis@google.com>
Subject: [PATCH] KVM: CPUID: Add new features to the guest's CPUID
Date: Mon, 15 Jul 2019 14:03:16 -0700
Message-ID: <20190715210316.25569-1-aaronlewis@google.com> (raw)

mask for CPUID.(EAX=07H,ECX=0H):EBX.  Doing this will ensure the guest's CPUID
for these bits match the host, rather than the guest being blindly set to 0.

This is important as these are actually defeature bits, which means that
a 0 indicates the presence of a feature and a 1 indicates the absence of
a feature.  since these features cannot be emulated, kvm should not
claim the existence of a feature that isn't present on the host.

Signed-off-by: Aaron Lewis <aaronlewis@google.com>
 arch/x86/kvm/cpuid.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index ead681210306..64c3fad068e1 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -353,7 +353,8 @@ static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry, int index)
 		F(BMI2) | F(ERMS) | f_invpcid | F(RTM) | f_mpx | F(RDSEED) |
 		F(ADX) | F(SMAP) | F(AVX512IFMA) | F(AVX512F) | F(AVX512PF) |
 		F(AVX512ER) | F(AVX512CD) | F(CLFLUSHOPT) | F(CLWB) | F(AVX512DQ) |
-		F(SHA_NI) | F(AVX512BW) | F(AVX512VL) | f_intel_pt;
+		F(SHA_NI) | F(AVX512BW) | F(AVX512VL) | f_intel_pt |
 	/* cpuid 7.0.ecx*/
 	const u32 kvm_cpuid_7_0_ecx_x86_features =

             reply index

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-15 21:03 Aaron Lewis [this message]
2019-07-22 14:51 ` Aaron Lewis
2019-07-23 21:42 ` Krish Sadhukhan
2019-08-21 16:17   ` Aaron Lewis

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