[Xen-devel] [PATCH for-next] x86/VT-x: Don't use rdmsr() to fill HOST_SYSENTER_{CS, EIP}

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

These are compile-time constants, and don't need to be read back from
hardware.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Wei Liu <wei.liu2@xxxxxxxxxx>
CC: Jun Nakajima <jun.nakajima@xxxxxxxxx>
CC: Kevin Tian <kevin.tian@xxxxxxxxx>
---
 xen/arch/x86/hvm/vmx/vmcs.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index 6042109..e7818ca 100644
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -994,8 +994,6 @@ static void pi_desc_init(struct vcpu *v)
 static int construct_vmcs(struct vcpu *v)
 {
     struct domain *d = v->domain;
-    uint16_t sysenter_cs;
-    unsigned long sysenter_eip;
     u32 vmexit_ctl = vmx_vmexit_control;
     u32 vmentry_ctl = vmx_vmentry_control;
 
@@ -1155,10 +1153,8 @@ static int construct_vmcs(struct vcpu *v)
     __vmwrite(HOST_RIP, (unsigned long)vmx_asm_vmexit_handler);
 
     /* Host SYSENTER CS:RIP. */
-    rdmsrl(MSR_IA32_SYSENTER_CS, sysenter_cs);
-    __vmwrite(HOST_SYSENTER_CS, sysenter_cs);
-    rdmsrl(MSR_IA32_SYSENTER_EIP, sysenter_eip);
-    __vmwrite(HOST_SYSENTER_EIP, sysenter_eip);
+    __vmwrite(HOST_SYSENTER_CS, __HYPERVISOR_CS);
+    __vmwrite(HOST_SYSENTER_EIP, (unsigned long)sysenter_entry);
 
     /* MSR intercepts. */
     __vmwrite(VM_EXIT_MSR_LOAD_COUNT, 0);
-- 
2.1.4


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