x86/msr: AMD MSR_SPEC_CTRL infrastructure

Fill in VMCB accessors for spec_ctrl in svm_{get,set}_reg(), and CPUID checks
for all supported bits in guest_{rd,wr}msr().

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>

xen/arch/x86/hvm/svm/svm.c

@@ -2471,10 +2471,14 @@ static bool svm_get_pending_event(struct vcpu *v, struct x86_event *info)
 
 static uint64_t svm_get_reg(struct vcpu *v, unsigned int reg)
 {
+    const struct vmcb_struct *vmcb = v->arch.hvm.svm.vmcb;
     struct domain *d = v->domain;
 
     switch ( reg )
     {
+    case MSR_SPEC_CTRL:
+        return vmcb->spec_ctrl;
+
     default:
         printk(XENLOG_G_ERR "%s(%pv, 0x%08x) Bad register\n",
                __func__, v, reg);
@@ -2485,10 +2489,15 @@ static uint64_t svm_get_reg(struct vcpu *v, unsigned int reg)
 
 static void svm_set_reg(struct vcpu *v, unsigned int reg, uint64_t val)
 {
+    struct vmcb_struct *vmcb = v->arch.hvm.svm.vmcb;
     struct domain *d = v->domain;
 
     switch ( reg )
     {
+    case MSR_SPEC_CTRL:
+        vmcb->spec_ctrl = val;
+        break;
+
     default:
         printk(XENLOG_G_ERR "%s(%pv, 0x%08x, 0x%016"PRIx64") Bad register\n",
                __func__, v, reg, val);

xen/arch/x86/msr.c

@@ -265,7 +265,7 @@ int guest_rdmsr(struct vcpu *v, uint32_t msr, uint64_t *val)
         break;
 
     case MSR_SPEC_CTRL:
-        if ( !cp->feat.ibrsb )
+        if ( !cp->feat.ibrsb && !cp->extd.ibrs )
             goto gp_fault;
         goto get_reg;
 
@@ -442,7 +442,8 @@ int guest_rdmsr(struct vcpu *v, uint32_t msr, uint64_t *val)
  */
 uint64_t msr_spec_ctrl_valid_bits(const struct cpuid_policy *cp)
 {
-    bool ssbd = cp->feat.ssbd;
+    bool ssbd = cp->feat.ssbd || cp->extd.amd_ssbd;
+    bool psfd = cp->extd.psfd;
 
     /*
      * Note: SPEC_CTRL_STIBP is specified as safe to use (i.e. ignored)
@@ -450,6 +451,7 @@ uint64_t msr_spec_ctrl_valid_bits(const struct cpuid_policy *cp)
      */
     return (SPEC_CTRL_IBRS | SPEC_CTRL_STIBP |
             (ssbd       ? SPEC_CTRL_SSBD       : 0) |
+            (psfd       ? SPEC_CTRL_PSFD       : 0) |
             0);
 }
 
@@ -526,7 +528,7 @@ int guest_wrmsr(struct vcpu *v, uint32_t msr, uint64_t val)
         break;
 
     case MSR_SPEC_CTRL:
-        if ( !cp->feat.ibrsb ||
+        if ( (!cp->feat.ibrsb && !cp->extd.ibrs) ||
              (val & ~msr_spec_ctrl_valid_bits(cp)) )
             goto gp_fault;
         goto set_reg;