viridian: use viridian_map/unmap_guest_page() for reference tsc page

Whilst the reference tsc page does not currently need to be kept mapped
after it is initially set up (or updated after migrate), the code can
be simplified by using the common guest page map/unmap and dump functions.
New functionality added by a subsequent patch will also require the page to
kept mapped for the lifetime of the domain.

NOTE: Because the reference tsc page is per-domain rather than per-vcpu
      this patch also changes viridian_map_guest_page() to take a domain
      pointer rather than a vcpu pointer. The domain pointer cannot be
      const, unlike the vcpu pointer.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Wei Liu <wei.liu2@citrix.com>

xen/arch/x86/hvm/viridian/private.h

@@ -111,7 +111,7 @@ void viridian_time_load_domain_ctxt(
 
 void viridian_dump_guest_page(const struct vcpu *v, const char *name,
                               const struct viridian_page *vp);
-void viridian_map_guest_page(const struct vcpu *v, struct viridian_page *vp);
+void viridian_map_guest_page(struct domain *d, struct viridian_page *vp);
 void viridian_unmap_guest_page(struct viridian_page *vp);
 
 #endif /* X86_HVM_VIRIDIAN_PRIVATE_H */

xen/arch/x86/hvm/viridian/synic.c

@@ -81,6 +81,7 @@ void viridian_apic_assist_clear(const struct vcpu *v)
 int viridian_synic_wrmsr(struct vcpu *v, uint32_t idx, uint64_t val)
 {
     struct viridian_vcpu *vv = v->arch.hvm.viridian;
+    struct domain *d = v->domain;
 
     switch ( idx )
     {
@@ -103,7 +104,7 @@ int viridian_synic_wrmsr(struct vcpu *v, uint32_t idx, uint64_t val)
         vv->vp_assist.msr.raw = val;
         viridian_dump_guest_page(v, "VP_ASSIST", &vv->vp_assist);
         if ( vv->vp_assist.msr.enabled )
-            viridian_map_guest_page(v, &vv->vp_assist);
+            viridian_map_guest_page(d, &vv->vp_assist);
         break;
 
     default:
@@ -178,10 +179,11 @@ void viridian_synic_load_vcpu_ctxt(
     struct vcpu *v, const struct hvm_viridian_vcpu_context *ctxt)
 {
     struct viridian_vcpu *vv = v->arch.hvm.viridian;
+    struct domain *d = v->domain;
 
     vv->vp_assist.msr.raw = ctxt->vp_assist_msr;
     if ( vv->vp_assist.msr.enabled )
-        viridian_map_guest_page(v, &vv->vp_assist);
+        viridian_map_guest_page(d, &vv->vp_assist);
 
     vv->apic_assist_pending = ctxt->apic_assist_pending;
 }

xen/arch/x86/hvm/viridian/time.c

@@ -25,33 +25,10 @@ typedef struct _HV_REFERENCE_TSC_PAGE
     uint64_t Reserved2[509];
 } HV_REFERENCE_TSC_PAGE, *PHV_REFERENCE_TSC_PAGE;
 
-static void dump_reference_tsc(const struct domain *d)
-{
-    const union viridian_page_msr *rt = &d->arch.hvm.viridian->reference_tsc;
-
-    if ( !rt->enabled )
-        return;
-
-    printk(XENLOG_G_INFO "d%d: VIRIDIAN REFERENCE_TSC: pfn: %lx\n",
-           d->domain_id, (unsigned long)rt->pfn);
-}
-
 static void update_reference_tsc(struct domain *d, bool initialize)
 {
-    unsigned long gmfn = d->arch.hvm.viridian->reference_tsc.pfn;
-    struct page_info *page = get_page_from_gfn(d, gmfn, NULL, P2M_ALLOC);
-    HV_REFERENCE_TSC_PAGE *p;
-
-    if ( !page || !get_page_type(page, PGT_writable_page) )
-    {
-        if ( page )
-            put_page(page);
-        gdprintk(XENLOG_WARNING, "Bad GMFN %#"PRI_gfn" (MFN %#"PRI_mfn")\n",
-                 gmfn, mfn_x(page ? page_to_mfn(page) : INVALID_MFN));
-        return;
-    }
-
-    p = __map_domain_page(page);
+    const struct viridian_page *rt = &d->arch.hvm.viridian->reference_tsc;
+    HV_REFERENCE_TSC_PAGE *p = rt->ptr;
 
     if ( initialize )
         clear_page(p);
@@ -82,7 +59,7 @@ static void update_reference_tsc(struct domain *d, bool initialize)
 
         printk(XENLOG_G_INFO "d%d: VIRIDIAN REFERENCE_TSC: invalidated\n",
                d->domain_id);
-        goto out;
+        return;
     }
 
     /*
@@ -100,11 +77,6 @@ static void update_reference_tsc(struct domain *d, bool initialize)
     if ( p->TscSequence == 0xFFFFFFFF ||
          p->TscSequence == 0 ) /* Avoid both 'invalid' values */
         p->TscSequence = 1;
-
- out:
-    unmap_domain_page(p);
-
-    put_page_and_type(page);
 }
 
 static int64_t raw_trc_val(const struct domain *d)
@@ -149,10 +121,14 @@ int viridian_time_wrmsr(struct vcpu *v, uint32_t idx, uint64_t val)
         if ( !(viridian_feature_mask(d) & HVMPV_reference_tsc) )
             return X86EMUL_EXCEPTION;
 
-        vd->reference_tsc.raw = val;
-        dump_reference_tsc(d);
-        if ( vd->reference_tsc.enabled )
+        viridian_unmap_guest_page(&vd->reference_tsc);
+        vd->reference_tsc.msr.raw = val;
+        viridian_dump_guest_page(v, "REFERENCE_TSC", &vd->reference_tsc);
+        if ( vd->reference_tsc.msr.enabled )
+        {
+            viridian_map_guest_page(d, &vd->reference_tsc);
             update_reference_tsc(d, true);
+        }
         break;
 
     default:
@@ -189,7 +165,7 @@ int viridian_time_rdmsr(const struct vcpu *v, uint32_t idx, uint64_t *val)
         if ( !(viridian_feature_mask(d) & HVMPV_reference_tsc) )
             return X86EMUL_EXCEPTION;
 
-        *val = vd->reference_tsc.raw;
+        *val = vd->reference_tsc.msr.raw;
         break;
 
     case HV_X64_MSR_TIME_REF_COUNT:
@@ -231,6 +207,7 @@ void viridian_time_vcpu_deinit(const struct vcpu *v)
 
 void viridian_time_domain_deinit(const struct domain *d)
 {
+    viridian_unmap_guest_page(&d->arch.hvm.viridian->reference_tsc);
 }
 
 void viridian_time_save_vcpu_ctxt(
@@ -249,7 +226,7 @@ void viridian_time_save_domain_ctxt(
     const struct viridian_domain *vd = d->arch.hvm.viridian;
 
     ctxt->time_ref_count = vd->time_ref_count.val;
-    ctxt->reference_tsc = vd->reference_tsc.raw;
+    ctxt->reference_tsc = vd->reference_tsc.msr.raw;
 }
 
 void viridian_time_load_domain_ctxt(
@@ -258,11 +235,14 @@ void viridian_time_load_domain_ctxt(
     struct viridian_domain *vd = d->arch.hvm.viridian;
 
     vd->time_ref_count.val = ctxt->time_ref_count;
-    vd->reference_tsc.raw = ctxt->reference_tsc;
+    vd->reference_tsc.msr.raw = ctxt->reference_tsc;
 
-    if ( vd->reference_tsc.enabled )
+    if ( vd->reference_tsc.msr.enabled )
+    {
+        viridian_map_guest_page(d, &vd->reference_tsc);
         update_reference_tsc(d, false);
     }
+}
 
 /*
  * Local variables:

xen/arch/x86/hvm/viridian/viridian.c

@@ -644,9 +644,8 @@ void viridian_dump_guest_page(const struct vcpu *v, const char *name,
            v, name, (unsigned long)vp->msr.pfn);
 }
 
-void viridian_map_guest_page(const struct vcpu *v, struct viridian_page *vp)
+void viridian_map_guest_page(struct domain *d, struct viridian_page *vp)
 {
-    struct domain *d = v->domain;
     unsigned long gmfn = vp->msr.pfn;
     struct page_info *page;
 

xen/include/asm-x86/hvm/viridian.h

@@ -65,7 +65,7 @@ struct viridian_domain
     union viridian_guest_os_id_msr guest_os_id;
     union viridian_page_msr hypercall_gpa;
     struct viridian_time_ref_count time_ref_count;
-    union viridian_page_msr reference_tsc;
+    struct viridian_page reference_tsc;
 };
 
 void cpuid_viridian_leaves(const struct vcpu *v, uint32_t leaf,