linux-kernel - [PATCH 01/15] KVM: VMX: Use x86 core API to access to fs_base and inactive gs

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Message-Id: <20211118110814.2568-2-jiangshanlai@gmail.com>
Date:   Thu, 18 Nov 2021 19:08:00 +0800
From:   Lai Jiangshan <jiangshanlai@...il.com>
To:     linux-kernel@...r.kernel.org
Cc:     kvm@...r.kernel.org, Lai Jiangshan <laijs@...ux.alibaba.com>,
        x86@...nel.org, Paolo Bonzini <pbonzini@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>, Kees Cook <keescook@...omium.org>
Subject: [PATCH 01/15] KVM: VMX: Use x86 core API to access to fs_base and inactive gs_base

From: Lai Jiangshan <laijs@...ux.alibaba.com>

And they use FSGSBASE instructions when enabled.

Cc: x86@...nel.org
Signed-off-by: Lai Jiangshan <laijs@...ux.alibaba.com>
---
 arch/x86/include/asm/kvm_host.h | 10 ----------
 arch/x86/kernel/process_64.c    |  2 ++
 arch/x86/kvm/vmx/vmx.c          | 14 +++++++-------
 3 files changed, 9 insertions(+), 17 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 1fcb345bc107..4cbb402f5636 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1808,16 +1808,6 @@ static inline void kvm_load_ldt(u16 sel)
 	asm("lldt %0" : : "rm"(sel));
 }
 
-#ifdef CONFIG_X86_64
-static inline unsigned long read_msr(unsigned long msr)
-{
-	u64 value;
-
-	rdmsrl(msr, value);
-	return value;
-}
-#endif
-
 static inline void kvm_inject_gp(struct kvm_vcpu *vcpu, u32 error_code)
 {
 	kvm_queue_exception_e(vcpu, GP_VECTOR, error_code);
diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index 3402edec236c..296bd5c2e38b 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -443,6 +443,7 @@ unsigned long x86_gsbase_read_cpu_inactive(void)
 
 	return gsbase;
 }
+EXPORT_SYMBOL_GPL(x86_gsbase_read_cpu_inactive);
 
 void x86_gsbase_write_cpu_inactive(unsigned long gsbase)
 {
@@ -456,6 +457,7 @@ void x86_gsbase_write_cpu_inactive(unsigned long gsbase)
 		wrmsrl(MSR_KERNEL_GS_BASE, gsbase);
 	}
 }
+EXPORT_SYMBOL_GPL(x86_gsbase_write_cpu_inactive);
 
 unsigned long x86_fsbase_read_task(struct task_struct *task)
 {
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 3127c66a1651..48a34d1a2989 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -1156,11 +1156,11 @@ void vmx_prepare_switch_to_guest(struct kvm_vcpu *vcpu)
 	} else {
 		savesegment(fs, fs_sel);
 		savesegment(gs, gs_sel);
-		fs_base = read_msr(MSR_FS_BASE);
-		vmx->msr_host_kernel_gs_base = read_msr(MSR_KERNEL_GS_BASE);
+		fs_base = x86_fsbase_read_cpu();
+		vmx->msr_host_kernel_gs_base = x86_gsbase_read_cpu_inactive();
 	}
 
-	wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_guest_kernel_gs_base);
+	x86_gsbase_write_cpu_inactive(vmx->msr_guest_kernel_gs_base);
 #else
 	savesegment(fs, fs_sel);
 	savesegment(gs, gs_sel);
@@ -1184,7 +1184,7 @@ static void vmx_prepare_switch_to_host(struct vcpu_vmx *vmx)
 	++vmx->vcpu.stat.host_state_reload;
 
 #ifdef CONFIG_X86_64
-	rdmsrl(MSR_KERNEL_GS_BASE, vmx->msr_guest_kernel_gs_base);
+	vmx->msr_guest_kernel_gs_base = x86_gsbase_read_cpu_inactive();
 #endif
 	if (host_state->ldt_sel || (host_state->gs_sel & 7)) {
 		kvm_load_ldt(host_state->ldt_sel);
@@ -1204,7 +1204,7 @@ static void vmx_prepare_switch_to_host(struct vcpu_vmx *vmx)
 #endif
 	invalidate_tss_limit();
 #ifdef CONFIG_X86_64
-	wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_host_kernel_gs_base);
+	x86_gsbase_write_cpu_inactive(vmx->msr_host_kernel_gs_base);
 #endif
 	load_fixmap_gdt(raw_smp_processor_id());
 	vmx->guest_state_loaded = false;
@@ -1216,7 +1216,7 @@ static u64 vmx_read_guest_kernel_gs_base(struct vcpu_vmx *vmx)
 {
 	preempt_disable();
 	if (vmx->guest_state_loaded)
-		rdmsrl(MSR_KERNEL_GS_BASE, vmx->msr_guest_kernel_gs_base);
+		vmx->msr_guest_kernel_gs_base = x86_gsbase_read_cpu_inactive();
 	preempt_enable();
 	return vmx->msr_guest_kernel_gs_base;
 }
@@ -1225,7 +1225,7 @@ static void vmx_write_guest_kernel_gs_base(struct vcpu_vmx *vmx, u64 data)
 {
 	preempt_disable();
 	if (vmx->guest_state_loaded)
-		wrmsrl(MSR_KERNEL_GS_BASE, data);
+		x86_gsbase_write_cpu_inactive(data);
 	preempt_enable();
 	vmx->msr_guest_kernel_gs_base = data;
 }
-- 
2.19.1.6.gb485710b