linux-kernel - [PATCH RFC 1/3] x86/kvm/vmx: read MSR_FS

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Date:   Fri,  2 Mar 2018 11:55:01 +0100
From:   Vitaly Kuznetsov <vkuznets@...hat.com>
To:     kvm@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        Paolo Bonzini <pbonzini@...hat.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, Andy Lutomirski <luto@...nel.org>
Subject: [PATCH RFC 1/3] x86/kvm/vmx: read MSR_FS_BASE from current->thread

vmx_save_host_state() is only called from kvm_arch_vcpu_ioctl_run() so
the context is pretty well defined and MSR_FS_BASE should always be
equal to current->thread.fsbase.

Signed-off-by: Vitaly Kuznetsov <vkuznets@...hat.com>
---
 arch/x86/kvm/vmx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index cab6ea1f8be5..ddefb7aeb96d 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2157,7 +2157,7 @@ static void vmx_save_host_state(struct kvm_vcpu *vcpu)
 #endif
 
 #ifdef CONFIG_X86_64
-	vmcs_writel(HOST_FS_BASE, read_msr(MSR_FS_BASE));
+	vmcs_writel(HOST_FS_BASE, current->thread.fsbase);
 	vmcs_writel(HOST_GS_BASE, read_msr(MSR_GS_BASE));
 #else
 	vmcs_writel(HOST_FS_BASE, segment_base(vmx->host_state.fs_sel));
-- 
2.14.3