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From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: kvm@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Ingo Molnar" <mingo@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"Andy Lutomirski" <luto@kernel.org>
Subject: [PATCH RFC 2/3] x86/kvm/vmx: read MSR_KERNEL_GS_BASE from current->thread
Date: Fri,  2 Mar 2018 11:55:02 +0100	[thread overview]
Message-ID: <20180302105503.24428-3-vkuznets@redhat.com> (raw)
In-Reply-To: <20180302105503.24428-1-vkuznets@redhat.com>

vmx_save_host_state() is only called from kvm_arch_vcpu_ioctl_run() so
the context is pretty well defined and as we're past 'swapgs'
MSR_KERNEL_GS_BASE should be current->thread.gsbase.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.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 ddefb7aeb96d..5be34d13d88f 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2165,7 +2165,7 @@ static void vmx_save_host_state(struct kvm_vcpu *vcpu)
 #endif
 
 #ifdef CONFIG_X86_64
-	rdmsrl(MSR_KERNEL_GS_BASE, vmx->msr_host_kernel_gs_base);
+	vmx->msr_host_kernel_gs_base = current->thread.gsbase;
 	if (is_long_mode(&vmx->vcpu))
 		wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_guest_kernel_gs_base);
 #endif
-- 
2.14.3

  parent reply	other threads:[~2018-03-02 10:57 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-02 10:55 [PATCH RFC 0/3] x86/kvm: avoid expensive rdmsrs for FS/GS base MSRs Vitaly Kuznetsov
2018-03-02 10:55 ` [PATCH RFC 1/3] x86/kvm/vmx: read MSR_FS_BASE from current->thread Vitaly Kuznetsov
2018-03-02 20:18   ` Andy Lutomirski
2018-03-05  9:56     ` Vitaly Kuznetsov
2018-03-07 13:15     ` Vitaly Kuznetsov
2018-03-02 10:55 ` Vitaly Kuznetsov [this message]
2018-03-02 10:55 ` [PATCH RFC 3/3] x86/kvm/vmx: avoid expensive rdmsr for MSR_GS_BASE Vitaly Kuznetsov
2018-03-02 20:20   ` Andy Lutomirski
2018-03-05 10:04     ` Vitaly Kuznetsov
2018-03-06 10:16 ` [PATCH RFC 0/3] x86/kvm: avoid expensive rdmsrs for FS/GS base MSRs Paolo Bonzini

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