[Xen-devel] [PATCH v2 13/14] x86/cpuid: Handle leaf 0x8000001c in guest_cpuid()

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

Leaf 0x8000001c contains LWP information.  edx contains hardware supported
features (and is clamped against the maximum), while ecx and ebx contain
various properties of the implementation.  eax is entirely dynamic, depending
on xcr0 and MSR_LWP_CFG.

The call to guest_cpuid() in svm_update_lwp_cfg() can now be replaced by
reading the data straight out of the cpuid_policy block.

Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
CC: Jan Beulich <JBeulich@xxxxxxxx>
CC: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
CC: Suravee Suthikulpanit <suravee.suthikulpanit@xxxxxxx>
---
 xen/arch/x86/cpuid.c       | 34 ++++++++++++++++------------------
 xen/arch/x86/hvm/svm/svm.c |  5 +----
 2 files changed, 17 insertions(+), 22 deletions(-)

diff --git a/xen/arch/x86/cpuid.c b/xen/arch/x86/cpuid.c
index b9dcc71..78cd287 100644
--- a/xen/arch/x86/cpuid.c
+++ b/xen/arch/x86/cpuid.c
@@ -213,6 +213,8 @@ static void recalculate_misc(struct cpuid_policy *p)
         zero_leaves(p->extd.raw, 0xb, 0x18);
 
         p->extd.raw[0x1b] = EMPTY_LEAF; /* IBS - not supported. */
+
+        p->extd.raw[0x1c].a = 0; /* LWP.a entirely dynamic. */
         break;
     }
 }
@@ -513,6 +515,11 @@ void recalculate_cpuid_policy(struct domain *d)
 
     if ( !p->extd.svm )
         p->extd.raw[0xa] = EMPTY_LEAF;
+
+    if ( p->extd.lwp )
+        p->extd.raw[0x1c].d &= max->extd.raw[0x1c].d;
+    else
+        p->extd.raw[0x1c] = EMPTY_LEAF;
 }
 
 int init_domain_cpuid_policy(struct domain *d)
@@ -726,7 +733,6 @@ static void pv_cpuid(uint32_t leaf, uint32_t subleaf, 
struct cpuid_leaf *res)
 
     case 0x00000005: /* MONITOR/MWAIT */
     case 0x0000000b: /* Extended Topology Enumeration */
-    case 0x8000001c: /* Light Weight Profiling */
     unsupported:
         *res = EMPTY_LEAF;
         break;
@@ -735,7 +741,7 @@ static void pv_cpuid(uint32_t leaf, uint32_t subleaf, 
struct cpuid_leaf *res)
     case 0x2 ... 0x3:
     case 0x7 ... 0x9:
     case 0xc ... XSTATE_CPUID:
-    case 0x80000000 ... 0x8000001b:
+    case 0x80000000 ... 0x8000001c:
         ASSERT_UNREACHABLE();
         /* Now handled in guest_cpuid(). */
     }
@@ -813,25 +819,11 @@ static void hvm_cpuid(uint32_t leaf, uint32_t subleaf, 
struct cpuid_leaf *res)
             res->a = (res->a & ~0xff) | 3;
         break;
 
-    case 0x8000001c:
-        if ( !cpu_has_svm )
-        {
-            *res = EMPTY_LEAF;
-            break;
-        }
-
-        if ( cpu_has_lwp && (v->arch.xcr0 & XSTATE_LWP) )
-            /* Turn on available bit and other features specified in lwp_cfg. 
*/
-            res->a = (res->d & v->arch.hvm_svm.guest_lwp_cfg) | 1;
-        else
-            res->a = 0;
-        break;
-
     case 0x0:
     case 0x2 ... 0x3:
     case 0x7 ... 0x9:
     case 0xc ... XSTATE_CPUID:
-    case 0x80000000 ... 0x8000001b:
+    case 0x80000000 ... 0x8000001c:
         ASSERT_UNREACHABLE();
         /* Now handled in guest_cpuid(). */
     }
@@ -914,7 +906,7 @@ void guest_cpuid(const struct vcpu *v, uint32_t leaf,
         default:
             goto legacy;
 
-        case 0x80000000 ... 0x8000001b:
+        case 0x80000000 ... 0x8000001c:
             *res = p->extd.raw[leaf & 0xffff];
             break;
         }
@@ -1024,6 +1016,12 @@ void guest_cpuid(const struct vcpu *v, uint32_t leaf,
                 res->d |= cpufeat_mask(X86_FEATURE_MTRR);
         }
         break;
+
+    case 0x8000001c:
+        if ( (v->arch.xcr0 & XSTATE_LWP) && cpu_has_svm )
+            /* Turn on available bit and other features specified in lwp_cfg. 
*/
+            res->a = (res->d & v->arch.hvm_svm.guest_lwp_cfg) | 1;
+        break;
     }
 
     /* Done. */
diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
index e8ef88d..01c7b58 100644
--- a/xen/arch/x86/hvm/svm/svm.c
+++ b/xen/arch/x86/hvm/svm/svm.c
@@ -931,13 +931,10 @@ static int svm_update_lwp_cfg(struct vcpu *v, uint64_t 
msr_content)
 
     if ( xsave_enabled(v) && cpu_has_lwp )
     {
-        struct cpuid_leaf res;
-
-        guest_cpuid(v, 0x8000001c, 0, &res);
         msr_low = (uint32_t)msr_content;
         
         /* generate #GP if guest tries to turn on unsupported features. */
-        if ( msr_low & ~res.d)
+        if ( msr_low & ~v->domain->arch.cpuid->extd.raw[0x1c].d )
             return -1;
 
         v->arch.hvm_svm.guest_lwp_cfg = msr_content;
-- 
2.1.4


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