The HOST_{FS,GS}_BASE fields are guaranteed to be written prior to
VMENTER, by way of vmx_prepare_switch_to_guest(). Initialize the
fields to zero for 64-bit kernels instead of pulling the base values
from their respective MSRs. In addition to eliminating two RDMSRs,
vmx_prepare_switch_to_guest() can safely assume the initial value of
the fields is zero in all cases.
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
---
arch/x86/kvm/vmx.c | 10 ----------
1 file changed, 10 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index c66fcb01f355..b24cd74c905c 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -6223,9 +6223,6 @@ static void ept_set_mmio_spte_mask(void)
*/
static void vmx_vcpu_setup(struct vcpu_vmx *vmx)
{
-#ifdef CONFIG_X86_64
- unsigned long a;
-#endif
int i;
if (enable_shadow_vmcs) {
@@ -6280,15 +6277,8 @@ static void vmx_vcpu_setup(struct vcpu_vmx *vmx)
vmcs_write16(HOST_FS_SELECTOR, 0); /* 22.2.4 */
vmcs_write16(HOST_GS_SELECTOR, 0); /* 22.2.4 */
vmx_set_constant_host_state(vmx);
-#ifdef CONFIG_X86_64
- rdmsrl(MSR_FS_BASE, a);
- vmcs_writel(HOST_FS_BASE, a); /* 22.2.4 */
- rdmsrl(MSR_GS_BASE, a);
- vmcs_writel(HOST_GS_BASE, a); /* 22.2.4 */
-#else
vmcs_writel(HOST_FS_BASE, 0); /* 22.2.4 */
vmcs_writel(HOST_GS_BASE, 0); /* 22.2.4 */
-#endif
if (cpu_has_vmx_vmfunc())
vmcs_write64(VM_FUNCTION_CONTROL, 0);
--
2.18.0
