x86/vmx: API improvements for MSR load/save infrastructure

Collect together related infrastructure in vmcs.h, rather than having it
spread out.  Turn vmx_{read,write}_guest_msr() into static inlines, as they
are simple enough.

Replace 'int type' with 'enum vmx_msr_list_type', and use switch statements
internally.  Later changes are going to introduce a new type.

Rename the type identifiers for consistency with the other VMX_MSR_*
constants.

No functional change.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Kevin Tian <kevin.tian@intel.com>
(cherry picked from commit f54b63e861)

xen/arch/x86/hvm/vmx/vmcs.c

@@ -1312,58 +1312,62 @@ static int construct_vmcs(struct vcpu *v)
     return rc;
 }
 
-int vmx_read_guest_msr(u32 msr, u64 *val)
+struct vmx_msr_entry *vmx_find_msr(uint32_t msr, enum vmx_msr_list_type type)
 {
     struct vcpu *curr = current;
-    unsigned int i, msr_count = curr->arch.hvm_vmx.msr_count;
-    const struct vmx_msr_entry *msr_area = curr->arch.hvm_vmx.msr_area;
+    unsigned int msr_count;
+    struct vmx_msr_entry *msr_area = NULL;
+    unsigned int i;
+
+    switch ( type )
+    {
+    case VMX_MSR_HOST:
+        msr_count = curr->arch.hvm_vmx.host_msr_count;
+        msr_area = curr->arch.hvm_vmx.host_msr_area;
+        break;
+
+    case VMX_MSR_GUEST:
+        msr_count = curr->arch.hvm_vmx.msr_count;
+        msr_area = curr->arch.hvm_vmx.msr_area;
+        break;
+
+    default:
+        ASSERT_UNREACHABLE();
+    }
+
+    if ( msr_area == NULL )
+        return NULL;
 
     for ( i = 0; i < msr_count; i++ )
     {
         if ( msr_area[i].index == msr )
-        {
-            *val = msr_area[i].data;
-            return 0;
-        }
+            return &msr_area[i];
     }
 
-    return -ESRCH;
+    return NULL;
 }
 
-int vmx_write_guest_msr(u32 msr, u64 val)
-{
-    struct vcpu *curr = current;
-    unsigned int i, msr_count = curr->arch.hvm_vmx.msr_count;
-    struct vmx_msr_entry *msr_area = curr->arch.hvm_vmx.msr_area;
-
-    for ( i = 0; i < msr_count; i++ )
-    {
-        if ( msr_area[i].index == msr )
-        {
-            msr_area[i].data = val;
-            return 0;
-        }
-    }
-
-    return -ESRCH;
-}
-
-int vmx_add_msr(u32 msr, int type)
+int vmx_add_msr(uint32_t msr, enum vmx_msr_list_type type)
 {
     struct vcpu *curr = current;
     unsigned int idx, *msr_count;
     struct vmx_msr_entry **msr_area, *msr_area_elem;
 
-    if ( type == VMX_GUEST_MSR )
+    switch ( type )
     {
-        msr_count = &curr->arch.hvm_vmx.msr_count;
-        msr_area = &curr->arch.hvm_vmx.msr_area;
-    }
-    else
-    {
-        ASSERT(type == VMX_HOST_MSR);
+    case VMX_MSR_HOST:
         msr_count = &curr->arch.hvm_vmx.host_msr_count;
         msr_area = &curr->arch.hvm_vmx.host_msr_area;
+        break;
+
+    case VMX_MSR_GUEST:
+        msr_count = &curr->arch.hvm_vmx.msr_count;
+        msr_area = &curr->arch.hvm_vmx.msr_area;
+        break;
+
+    default:
+        ASSERT_UNREACHABLE();
+        return -EINVAL;
     }
 
     if ( *msr_area == NULL )
@@ -1371,13 +1375,17 @@ int vmx_add_msr(u32 msr, int type)
         if ( (*msr_area = alloc_xenheap_page()) == NULL )
             return -ENOMEM;
 
-        if ( type == VMX_GUEST_MSR )
+        switch ( type )
         {
+        case VMX_MSR_HOST:
+            __vmwrite(VM_EXIT_MSR_LOAD_ADDR, virt_to_maddr(*msr_area));
+            break;
+
+        case VMX_MSR_GUEST:
             __vmwrite(VM_EXIT_MSR_STORE_ADDR, virt_to_maddr(*msr_area));
             __vmwrite(VM_ENTRY_MSR_LOAD_ADDR, virt_to_maddr(*msr_area));
+            break;
         }
-        else
-            __vmwrite(VM_EXIT_MSR_LOAD_ADDR, virt_to_maddr(*msr_area));
     }
 
     for ( idx = 0; idx < *msr_count; idx++ )
@@ -1393,16 +1401,18 @@ int vmx_add_msr(u32 msr, int type)
 
     ++*msr_count;
 
-    if ( type == VMX_GUEST_MSR )
+    switch ( type )
     {
+    case VMX_MSR_HOST:
+        rdmsrl(msr, msr_area_elem->data);
+        __vmwrite(VM_EXIT_MSR_LOAD_COUNT, *msr_count);
+        break;
+
+    case VMX_MSR_GUEST:
         msr_area_elem->data = 0;
         __vmwrite(VM_EXIT_MSR_STORE_COUNT, *msr_count);
         __vmwrite(VM_ENTRY_MSR_LOAD_COUNT, *msr_count);
-    }
-    else
-    {
-        rdmsrl(msr, msr_area_elem->data);
-        __vmwrite(VM_EXIT_MSR_LOAD_COUNT, *msr_count);
+        break;
     }
 
     return 0;

xen/include/asm-x86/hvm/vmx/vmcs.h

@@ -568,18 +568,56 @@ enum vmcs_field {
 #define MSR_TYPE_R 1
 #define MSR_TYPE_W 2
 
-#define VMX_GUEST_MSR 0
-#define VMX_HOST_MSR  1
-
 /* VM Instruction error numbers. */
 #define VMX_INSN_INVALID_CONTROL_STATE       7
 #define VMX_INSN_INVALID_HOST_STATE          8
 
+/* MSR load/save list infrastructure. */
+enum vmx_msr_list_type {
+    VMX_MSR_HOST,           /* MSRs loaded on VMExit.                   */
+    VMX_MSR_GUEST,          /* MSRs saved on VMExit, loaded on VMEntry. */
+};
+
+int vmx_add_msr(uint32_t msr, enum vmx_msr_list_type type);
+
+static inline int vmx_add_host_load_msr(uint32_t msr)
+{
+    return vmx_add_msr(msr, VMX_MSR_HOST);
+}
+
+static inline int vmx_add_guest_msr(uint32_t msr)
+{
+    return vmx_add_msr(msr, VMX_MSR_GUEST);
+}
+
+struct vmx_msr_entry *vmx_find_msr(uint32_t msr, enum vmx_msr_list_type type);
+
+static inline int vmx_read_guest_msr(uint32_t msr, uint64_t *val)
+{
+    const struct vmx_msr_entry *ent = vmx_find_msr(msr, VMX_MSR_GUEST);
+
+    if ( !ent )
+        return -ESRCH;
+
+    *val = ent->data;
+
+    return 0;
+}
+
+static inline int vmx_write_guest_msr(uint32_t msr, uint64_t val)
+{
+    struct vmx_msr_entry *ent = vmx_find_msr(msr, VMX_MSR_GUEST);
+
+    if ( !ent )
+        return -ESRCH;
+
+    ent->data = val;
+
+    return 0;
+}
+
 void vmx_disable_intercept_for_msr(struct vcpu *v, u32 msr, int type);
 void vmx_enable_intercept_for_msr(struct vcpu *v, u32 msr, int type);
-int vmx_read_guest_msr(u32 msr, u64 *val);
-int vmx_write_guest_msr(u32 msr, u64 val);
-int vmx_add_msr(u32 msr, int type);
 void vmx_vmcs_switch(paddr_t from, paddr_t to);
 void vmx_set_eoi_exit_bitmap(struct vcpu *v, u8 vector);
 void vmx_clear_eoi_exit_bitmap(struct vcpu *v, u8 vector);
@@ -589,15 +627,6 @@ void virtual_vmcs_exit(const struct vcpu *);
 u64 virtual_vmcs_vmread(const struct vcpu *, u32 encoding);
 void virtual_vmcs_vmwrite(const struct vcpu *, u32 encoding, u64 val);
 
-static inline int vmx_add_guest_msr(u32 msr)
-{
-    return vmx_add_msr(msr, VMX_GUEST_MSR);
-}
-static inline int vmx_add_host_load_msr(u32 msr)
-{
-    return vmx_add_msr(msr, VMX_HOST_MSR);
-}
-
 DECLARE_PER_CPU(bool_t, vmxon);
 
 bool_t vmx_vcpu_pml_enabled(const struct vcpu *v);