[PATCH v2 6/8] x86/hvm: Enable guest access to MSR_PKRS

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Have guest_{rd,wr}msr(), via hvm_{get,set}_reg(), access either the live
register, or stashed state, depending on context.  Include MSR_PKRS for
migration, and let the guest have full access.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Roger Pau Monné <roger.pau@xxxxxxxxxx>
CC: Wei Liu <wl@xxxxxxx>
CC: Kevin Tian <kevin.tian@xxxxxxxxx>

v2:
 * Rebase over the get/set_reg() infrastructure.
---
 xen/arch/x86/hvm/hvm.c     |  1 +
 xen/arch/x86/hvm/vmx/vmx.c | 17 +++++++++++++++++
 xen/arch/x86/msr.c         | 10 ++++++++++
 3 files changed, 28 insertions(+)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 927a221660e8..c6c1eea18003 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -1333,6 +1333,7 @@ static int cf_check hvm_load_cpu_xsave_states(
 static const uint32_t msrs_to_send[] = {
     MSR_SPEC_CTRL,
     MSR_INTEL_MISC_FEATURES_ENABLES,
+    MSR_PKRS,
     MSR_IA32_BNDCFGS,
     MSR_IA32_XSS,
     MSR_VIRT_SPEC_CTRL,
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index b1f493f009fd..57827779c305 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -657,6 +657,11 @@ static void cf_check vmx_cpuid_policy_changed(struct vcpu 
*v)
     else
         vmx_set_msr_intercept(v, MSR_FLUSH_CMD, VMX_MSR_RW);
 
+    if ( cp->feat.pks )
+        vmx_clear_msr_intercept(v, MSR_PKRS, VMX_MSR_RW);
+    else
+        vmx_set_msr_intercept(v, MSR_PKRS, VMX_MSR_RW);
+
  out:
     vmx_vmcs_exit(v);
 
@@ -2455,6 +2460,7 @@ static uint64_t cf_check vmx_get_reg(struct vcpu *v, 
unsigned int reg)
 {
     const struct vcpu *curr = current;
     struct domain *d = v->domain;
+    const struct vcpu_msrs *msrs = v->arch.msrs;
     uint64_t val = 0;
     int rc;
 
@@ -2471,6 +2477,9 @@ static uint64_t cf_check vmx_get_reg(struct vcpu *v, 
unsigned int reg)
         }
         return val;
 
+    case MSR_PKRS:
+        return (v == curr) ? rdpkrs() : msrs->pkrs;
+
     case MSR_SHADOW_GS_BASE:
         if ( v != curr )
             return v->arch.hvm.vmx.shadow_gs;
@@ -2499,6 +2508,8 @@ static uint64_t cf_check vmx_get_reg(struct vcpu *v, 
unsigned int reg)
 
 static void cf_check vmx_set_reg(struct vcpu *v, unsigned int reg, uint64_t 
val)
 {
+    const struct vcpu *curr = current;
+    struct vcpu_msrs *msrs = v->arch.msrs;
     struct domain *d = v->domain;
     int rc;
 
@@ -2514,6 +2525,12 @@ static void cf_check vmx_set_reg(struct vcpu *v, 
unsigned int reg, uint64_t val)
             domain_crash(d);
         }
         return;
+
+    case MSR_PKRS:
+        msrs->pkrs = val;
+        if ( v == curr )
+            wrpkrs(val);
+        return;
     }
 
     /* Logic which maybe requires remote VMCS acquisition. */
diff --git a/xen/arch/x86/msr.c b/xen/arch/x86/msr.c
index 317b154d244d..7ddf0078c3a2 100644
--- a/xen/arch/x86/msr.c
+++ b/xen/arch/x86/msr.c
@@ -325,6 +325,11 @@ int guest_rdmsr(struct vcpu *v, uint32_t msr, uint64_t 
*val)
         *val = 0;
         break;
 
+    case MSR_PKRS:
+        if ( !cp->feat.pks )
+            goto gp_fault;
+        goto get_reg;
+
     case MSR_X2APIC_FIRST ... MSR_X2APIC_LAST:
         if ( !is_hvm_domain(d) || v != curr )
             goto gp_fault;
@@ -616,6 +621,11 @@ int guest_wrmsr(struct vcpu *v, uint32_t msr, uint64_t val)
             break;
         goto gp_fault;
 
+    case MSR_PKRS:
+        if ( !cp->feat.pks || val != (uint32_t)val )
+            goto gp_fault;
+        goto set_reg;
+
     case MSR_X2APIC_FIRST ... MSR_X2APIC_LAST:
         if ( !is_hvm_domain(d) || v != curr )
             goto gp_fault;
-- 
2.11.0