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Commit 56c103ec authored by Liu, Jinsong's avatar Liu, Jinsong Committed by Paolo Bonzini
Browse files

KVM: x86: Fix xsave cpuid exposing bug 



From 00c920c96127d20d4c3bb790082700ae375c39a0 Mon Sep 17 00:00:00 2001
From: Liu Jinsong <jinsong.liu@intel.com>
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: default avatarLiu Jinsong <jinsong.liu@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent 49345f13

arch/x86/include/asm/xsave.h

+2 −0
Original line number Diff line number Diff line
@@ -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

arch/x86/kvm/cpuid.c

+3 −3
Original line number Diff line number Diff line
@@ -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);

arch/x86/kvm/x86.c

+5 −2
Original line number Diff line number Diff line
@@ -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;

}