>From 00c920c96127d20d4c3bb790082700ae375c39a0 Mon Sep 17 00:00:00 2001
From: Liu Jinsong <jinsong.liu@xxxxxxxxx>
Date: Fri, 21 Feb 2014 23:47:18 +0800
Subject: [PATCH] KVM: x86: Fix xsave cpuid exposing bug
EBX of cpuid(0xD, 0) is dynamic per XCR0 features enable/disable.
Bit 63 of XCR0 is reserved for future expansion.
Signed-off-by: Liu Jinsong <jinsong.liu@xxxxxxxxx>
---
arch/x86/include/asm/xsave.h | 2 ++
arch/x86/kvm/cpuid.c | 6 +++---
arch/x86/kvm/x86.c | 7 +++++--
3 files changed, 10 insertions(+), 5 deletions(-)
diff --git a/arch/x86/include/asm/xsave.h b/arch/x86/include/asm/xsave.h
index 5547389..dcd047b 100644
--- a/arch/x86/include/asm/xsave.h
+++ b/arch/x86/include/asm/xsave.h
@@ -13,6 +13,8 @@
#define XSTATE_BNDCSR 0x10
#define XSTATE_FPSSE (XSTATE_FP | XSTATE_SSE)
+/* Bit 63 of XCR0 is reserved for future expansion */
+#define XSTATE_EXTEND_MASK (~(XSTATE_FPSSE | (1ULL << 63)))
#define FXSAVE_SIZE 512
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index a951ae4..b241325 100644
--- a/arch/x86/kvm/cpuid.c
+++ b/arch/x86/kvm/cpuid.c
@@ -28,7 +28,7 @@ static u32 xstate_required_size(u64 xstate_bv)
int feature_bit = 0;
u32 ret = XSAVE_HDR_SIZE + XSAVE_HDR_OFFSET;
- xstate_bv &= ~XSTATE_FPSSE;
+ xstate_bv &= XSTATE_EXTEND_MASK;
while (xstate_bv) {
if (xstate_bv & 0x1) {
u32 eax, ebx, ecx, edx;
@@ -74,8 +74,8 @@ void kvm_update_cpuid(struct kvm_vcpu *vcpu)
vcpu->arch.guest_supported_xcr0 =
(best->eax | ((u64)best->edx << 32)) &
host_xcr0 & KVM_SUPPORTED_XCR0;
- vcpu->arch.guest_xstate_size =
- xstate_required_size(vcpu->arch.guest_supported_xcr0);
+ vcpu->arch.guest_xstate_size = best->ebx =
+ xstate_required_size(vcpu->arch.xcr0);
}
kvm_pmu_cpuid_update(vcpu);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 39c28f0..7c52acb 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -595,13 +595,13 @@ static void kvm_put_guest_xcr0(struct kvm_vcpu *vcpu)
int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
{
- u64 xcr0;
+ u64 xcr0 = xcr;
+ u64 old_xcr0 = vcpu->arch.xcr0;
u64 valid_bits;
/* Only support XCR_XFEATURE_ENABLED_MASK(xcr0) now */
if (index != XCR_XFEATURE_ENABLED_MASK)
return 1;
- xcr0 = xcr;
if (!(xcr0 & XSTATE_FP))
return 1;
if ((xcr0 & XSTATE_YMM) && !(xcr0 & XSTATE_SSE))
@@ -618,6 +618,9 @@ int __kvm_set_xcr(struct kvm_vcpu *vcpu, u32 index, u64 xcr)
kvm_put_guest_xcr0(vcpu);
vcpu->arch.xcr0 = xcr0;
+
+ if ((xcr0 ^ old_xcr0) & XSTATE_EXTEND_MASK)
+ kvm_update_cpuid(vcpu);
return 0;
}
--
1.7.1
--
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