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| author |   Lai Jiangshan <laijs@linux.alibaba.com> | 2021-11-18 19:08:01 +0800 |
|---|---|---|
| committer |   Paolo Bonzini <pbonzini@redhat.com> | 2021-12-08 04:25:04 -0500 |
| commit | 6ab8a4053f7114d130fe1f3485d71efec20f5806 (patch) | |
| tree | 50ac917d7b3c86bd9936bc3168328564be8bea29 | |
| parent | KVM: X86: Update mmu->pdptrs only when it is changed (diff) | |
| download | linux-dev-6ab8a4053f7114d130fe1f3485d71efec20f5806.tar.xz linux-dev-6ab8a4053f7114d130fe1f3485d71efec20f5806.zip | |
KVM: VMX: Avoid to rdmsrl(MSR_IA32_SYSENTER_ESP)
The value of host MSR_IA32_SYSENTER_ESP is known to be constant for
each CPU: (cpu_entry_stack(cpu) + 1) when 32 bit syscall is enabled or
NULL is 32 bit syscall is not enabled.
So rdmsrl() can be avoided for the first case and both rdmsrl() and
vmcs_writel() can be avoided for the second case.
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
Message-Id: <20211118110814.2568-3-jiangshanlai@gmail.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
| -rw-r--r-- | arch/x86/kvm/vmx/vmx.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index c65ff62e11f5..56c46a50d85a 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -1271,7 +1271,6 @@ void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu, if (!already_loaded) { void *gdt = get_current_gdt_ro(); - unsigned long sysenter_esp; /* * Flush all EPTP/VPID contexts, the new pCPU may have stale @@ -1287,8 +1286,11 @@ void vmx_vcpu_load_vmcs(struct kvm_vcpu *vcpu, int cpu, (unsigned long)&get_cpu_entry_area(cpu)->tss.x86_tss); vmcs_writel(HOST_GDTR_BASE, (unsigned long)gdt); /* 22.2.4 */ - rdmsrl(MSR_IA32_SYSENTER_ESP, sysenter_esp); - vmcs_writel(HOST_IA32_SYSENTER_ESP, sysenter_esp); /* 22.2.3 */ + if (IS_ENABLED(CONFIG_IA32_EMULATION) || IS_ENABLED(CONFIG_X86_32)) { + /* 22.2.3 */ + vmcs_writel(HOST_IA32_SYSENTER_ESP, + (unsigned long)(cpu_entry_stack(cpu) + 1)); + } vmx->loaded_vmcs->cpu = cpu; } @@ -4026,6 +4028,12 @@ void vmx_set_constant_host_state(struct vcpu_vmx *vmx) rdmsr(MSR_IA32_SYSENTER_CS, low32, high32); vmcs_write32(HOST_IA32_SYSENTER_CS, low32); + + /* + * If 32-bit syscall is enabled, vmx_vcpu_load_vcms rewrites + * HOST_IA32_SYSENTER_ESP. + */ + vmcs_writel(HOST_IA32_SYSENTER_ESP, 0); rdmsrl(MSR_IA32_SYSENTER_EIP, tmpl); vmcs_writel(HOST_IA32_SYSENTER_EIP, tmpl); /* 22.2.3 */ |