[Xen-devel] [PATCH v2 04/14] x86/cpuid: Handle more simple Intel leaves in guest_cpuid()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Intel now document leaf 2 as a plain leaf, with %al always containing the
value 0x01.  Collect this leaf normally in calculate_raw_policy() and expose
it to guests.  The leaf is reserved by AMD.

Intel leaves 3 and 9 (PSN and DCA respectively) are not exposed to guests at
all.  They are reserved by AMD.

Leaves 8 and 0xc are reserved by both vendors.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>

v2:
 * New
---
 xen/arch/x86/cpuid.c        | 32 ++++++++++++++++++++++++++------
 xen/include/asm-x86/cpuid.h |  3 +++
 2 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/xen/arch/x86/cpuid.c b/xen/arch/x86/cpuid.c
index 87ec02f..7af5900 100644
--- a/xen/arch/x86/cpuid.c
+++ b/xen/arch/x86/cpuid.c
@@ -17,6 +17,11 @@ static const uint32_t hvm_hap_featuremask[] = 
INIT_HVM_HAP_FEATURES;
 static const uint32_t deep_features[] = INIT_DEEP_FEATURES;
 
 #define EMPTY_LEAF ((struct cpuid_leaf){})
+static void zero_leaves(struct cpuid_leaf *l,
+                        unsigned int first, unsigned int last)
+{
+    memset(&l[first], 0, sizeof(*l) * (last - first + 1));
+}
 
 struct cpuid_policy __read_mostly raw_policy,
     __read_mostly host_policy,
@@ -153,21 +158,31 @@ static void recalculate_xstate(struct cpuid_policy *p)
 
 /*
  * Misc adjustments to the policy.  Mostly clobbering reserved fields and
- * duplicating shared fields.
+ * duplicating shared fields.  Intentionally hidden fields are annotated.
  */
 static void recalculate_misc(struct cpuid_policy *p)
 {
+    p->basic.raw[0x8] = EMPTY_LEAF;
+    p->basic.raw[0xc] = EMPTY_LEAF;
+
     p->extd.e1d &= ~CPUID_COMMON_1D_FEATURES;
 
     switch ( p->x86_vendor )
     {
     case X86_VENDOR_INTEL:
+        p->basic.l2_nr_queries = 1; /* Fixed to 1 query. */
+        p->basic.raw[0x3] = EMPTY_LEAF; /* PSN - always hidden. */
+        p->basic.raw[0x9] = EMPTY_LEAF; /* DCA - always hidden. */
+
         p->extd.vendor_ebx = 0;
         p->extd.vendor_ecx = 0;
         p->extd.vendor_edx = 0;
         break;
 
     case X86_VENDOR_AMD:
+        zero_leaves(p->basic.raw, 0x2, 0x3);
+        p->basic.raw[0x9] = EMPTY_LEAF;
+
         p->extd.vendor_ebx = p->basic.vendor_ebx;
         p->extd.vendor_ecx = p->basic.vendor_ecx;
         p->extd.vendor_edx = p->basic.vendor_edx;
@@ -188,7 +203,7 @@ static void __init calculate_raw_policy(void)
     {
         switch ( i )
         {
-        case 0x2: case 0x4: case 0x7: case 0xd:
+        case 0x4: case 0x7: case 0xd:
             /* Multi-invocation leaves.  Deferred. */
             continue;
         }
@@ -694,8 +709,9 @@ static void pv_cpuid(uint32_t leaf, uint32_t subleaf, 
struct cpuid_leaf *res)
         break;
 
     case 0x0:
-    case 0x7:
-    case XSTATE_CPUID:
+    case 0x2 ... 0x3:
+    case 0x7 ... 0x9:
+    case 0xc ... XSTATE_CPUID:
     case 0x80000000:
         ASSERT_UNREACHABLE();
         /* Now handled in guest_cpuid(). */
@@ -841,8 +857,9 @@ static void hvm_cpuid(uint32_t leaf, uint32_t subleaf, 
struct cpuid_leaf *res)
         break;
 
     case 0x0:
-    case 0x7:
-    case XSTATE_CPUID:
+    case 0x2 ... 0x3:
+    case 0x7 ... 0x9:
+    case 0xc ... XSTATE_CPUID:
     case 0x80000000:
         ASSERT_UNREACHABLE();
         /* Now handled in guest_cpuid(). */
@@ -894,6 +911,9 @@ void guest_cpuid(const struct vcpu *v, uint32_t leaf,
             goto legacy;
 
         case 0x0:
+        case 0x2 ... 0x3:
+        case 0x8 ... 0x9:
+        case 0xc:
             *res = p->basic.raw[leaf];
             break;
         }
diff --git a/xen/include/asm-x86/cpuid.h b/xen/include/asm-x86/cpuid.h
index 4712b73..a15270a 100644
--- a/xen/include/asm-x86/cpuid.h
+++ b/xen/include/asm-x86/cpuid.h
@@ -115,6 +115,9 @@ struct cpuid_policy
                 uint32_t _1d;
                 struct { DECL_BITFIELD(1d); };
             };
+
+            /* Leaf 0x2 - TLB/Cache/Prefetch. */
+            uint8_t l2_nr_queries; /* Documented as fixed to 1. */
         };
     } basic;
 
-- 
2.1.4


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