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From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: kvm@vger.kernel.org, x86@kernel.org
Cc: linux-kernel@vger.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 2/3] x86/kvm/vmx: read MSR_KERNEL_GS_BASE from current->thread
Date: Mon, 12 Mar 2018 15:02:59 +0100	[thread overview]
Message-ID: <20180312140300.6166-3-vkuznets@redhat.com> (raw)
In-Reply-To: <20180312140300.6166-1-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 is equal to current->thread.gsbase (after previous
save_current_fsgs() call).

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 e46b7b24ebae..d4d9bb2fd91e 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2167,7 +2167,7 @@ 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:[~2018-03-12 14:04 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-12 14:02 [PATCH 0/3] x86/kvm: avoid expensive rdmsrs for FS/GS base MSRs Vitaly Kuznetsov
2018-03-12 14:02 ` [PATCH 1/3] x86/kvm/vmx: read MSR_FS_BASE from current->thread Vitaly Kuznetsov
2018-03-12 15:34   ` Andy Lutomirski
2018-03-12 15:55     ` Vitaly Kuznetsov
2018-03-12 16:03   ` Paolo Bonzini
2018-03-12 16:13     ` Andy Lutomirski
2018-03-12 16:18       ` Paolo Bonzini
2018-03-12 17:00         ` Andy Lutomirski
2018-03-12 17:11           ` Paolo Bonzini
2018-03-13 13:20     ` Vitaly Kuznetsov
2018-03-13 13:24       ` Paolo Bonzini
2018-03-12 14:02 ` Vitaly Kuznetsov [this message]
2018-03-12 14:03 ` [PATCH 3/3] x86/kvm/vmx: avoid expensive rdmsr for MSR_GS_BASE Vitaly Kuznetsov
2018-03-12 15:42   ` Andy Lutomirski

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