[PATCH v5 2/5] x86/hvm: Disable cross-vendor handling in #UD handler

[Alejandro Vallejo <alejandro.garciavallejo@xxxxxxx>]

Remove cross-vendor support now that VMs can no longer have a different
vendor than the host.

No functional change intended.

Signed-off-by: Alejandro Vallejo <alejandro.garciavallejo@xxxxxxx>
---
v5:
  * This patch now performs a minimal diff, with the other parts appended
    to the tail of the series.
---
 xen/arch/x86/hvm/hvm.c     | 19 ++-----------------
 xen/arch/x86/hvm/svm/svm.c |  3 +--
 xen/arch/x86/hvm/vmx/vmx.c |  3 +--
 3 files changed, 4 insertions(+), 21 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 4d37a93c57a..c8cae41705d 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -3832,28 +3832,13 @@ int hvm_descriptor_access_intercept(uint64_t exit_info,
     return X86EMUL_OKAY;
 }
 
-static bool cf_check is_cross_vendor(
-    const struct x86_emulate_state *state, const struct x86_emulate_ctxt *ctxt)
-{
-    switch ( ctxt->opcode )
-    {
-    case X86EMUL_OPC(0x0f, 0x05): /* syscall */
-    case X86EMUL_OPC(0x0f, 0x34): /* sysenter */
-    case X86EMUL_OPC(0x0f, 0x35): /* sysexit */
-        return true;
-    }
-
-    return false;
-}
-
 void hvm_ud_intercept(struct cpu_user_regs *regs)
 {
     struct vcpu *cur = current;
-    bool should_emulate =
-        cur->domain->arch.cpuid->x86_vendor != boot_cpu_data.x86_vendor;
+    bool should_emulate = false;
     struct hvm_emulate_ctxt ctxt;
 
-    hvm_emulate_init_once(&ctxt, opt_hvm_fep ? NULL : is_cross_vendor, regs);
+    hvm_emulate_init_once(&ctxt, NULL, regs);
 
     if ( opt_hvm_fep )
     {
diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index 243c41fb13a..20591c4a44f 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -589,8 +589,7 @@ static void cf_check svm_cpuid_policy_changed(struct vcpu 
*v)
     const struct cpu_policy *cp = v->domain->arch.cpu_policy;
     u32 bitmap = vmcb_get_exception_intercepts(vmcb);
 
-    if ( opt_hvm_fep ||
-         (v->domain->arch.cpuid->x86_vendor != boot_cpu_data.x86_vendor) )
+    if ( opt_hvm_fep )
         bitmap |= (1U << X86_EXC_UD);
     else
         bitmap &= ~(1U << X86_EXC_UD);
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 82c55f49aea..eda99e268d1 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -803,8 +803,7 @@ static void cf_check vmx_cpuid_policy_changed(struct vcpu 
*v)
     const struct cpu_policy *cp = v->domain->arch.cpu_policy;
     int rc = 0;
 
-    if ( opt_hvm_fep ||
-         (v->domain->arch.cpuid->x86_vendor != boot_cpu_data.x86_vendor) )
+    if ( opt_hvm_fep )
         v->arch.hvm.vmx.exception_bitmap |= (1U << X86_EXC_UD);
     else
         v->arch.hvm.vmx.exception_bitmap &= ~(1U << X86_EXC_UD);
-- 
2.43.0