linux-kernel - [PATCH 2/2] KVM: X86: XCR0 should be set to the fixed value on vCPU reset

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Date:   Sat,  7 Oct 2017 19:35:07 -0700
From:   Wanpeng Li <kernellwp@...il.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Wanpeng Li <wanpeng.li@...mail.com>
Subject: [PATCH 2/2] KVM: X86: XCR0 should be set to the fixed value on vCPU reset

From: Wanpeng Li <wanpeng.li@...mail.com>

SDM section 2.6 mentioned: 

After reset, all bits (except bit 0) in XCR0 are cleared to zero; XCR0[0] is set to 1.

This patch sets XCRO to the 0x1 after vCPU reset.

Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Radim Krčmář <rkrcmar@...hat.com>
Signed-off-by: Wanpeng Li <wanpeng.li@...mail.com>
---
 arch/x86/kvm/x86.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index b0d2915..c784cd6 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -7816,6 +7816,8 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
 	vcpu->arch.regs_avail = ~0;
 	vcpu->arch.regs_dirty = ~0;
 
+	vcpu->arch.xcr0 = XFEATURE_MASK_FP;
+
 	kvm_x86_ops->vcpu_reset(vcpu, init_event);
 }
 
-- 
2.7.4