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Commit f3bbc0dc authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
Browse files

KVM: vmx: always initialize HOST_{FS,GS}_BASE to zero during setup 



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: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent d7ee039e

arch/x86/kvm/vmx.c

+0 −10
Original line number Diff line number Diff line
@@ -6361,9 +6361,6 @@ 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) {
@@ -6418,15 +6415,8 @@ 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);