The current CPU's TSS base is a foregone conclusion, so there's no need
to parse it out of the segment tables. This should save a couple cycles
(as STR is surely microcoded and poorly optimized) but, more importantly,
it's a cleanup and it means that segment_base() will never be called on
64-bit kernels.
Cc: Thomas Garnier <thgarnie@xxxxxxxxxx>
Cc: Jim Mattson <jmattson@xxxxxxxxxx>
Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Signed-off-by: Andy Lutomirski <luto@xxxxxxxxxx>
---
arch/x86/kvm/vmx.c | 14 ++++----------
1 file changed, 4 insertions(+), 10 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index a236decb81e4..46420aaf1684 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -2088,13 +2088,6 @@ static unsigned long segment_base(u16 selector)
return v;
}
-static inline unsigned long kvm_read_tr_base(void)
-{
- u16 tr;
- asm("str %0" : "=g"(tr));
- return segment_base(tr);
-}
-
static void vmx_save_host_state(struct kvm_vcpu *vcpu)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
@@ -2294,10 +2287,11 @@ static void vmx_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
/*
* Linux uses per-cpu TSS and GDT, so set these when switching
- * processors.
+ * processors. See 22.2.4.
*/
- vmcs_writel(HOST_TR_BASE, kvm_read_tr_base()); /* 22.2.4 */
- vmcs_writel(HOST_GDTR_BASE, gdt->address); /* 22.2.4 */
+ vmcs_writel(HOST_TR_BASE,
+ (unsigned long)this_cpu_ptr(&cpu_tss));
+ vmcs_writel(HOST_GDTR_BASE, gdt->address);
rdmsrl(MSR_IA32_SYSENTER_ESP, sysenter_esp);
vmcs_writel(HOST_IA32_SYSENTER_ESP, sysenter_esp); /* 22.2.3 */
--
2.9.3
