From: Jan Beulich <jbeulich@suse.com>
Date: Thu, 2 Jun 2016 07:40:08 +0000 (+0200)
Subject: x86: flush high xstate CPUID sub-leaves to zero
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~1069
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=75cb0a1325d1b65fd64591a07e8476d5cfabba01;p=xen.git

x86: flush high xstate CPUID sub-leaves to zero

In line with other recent changes, these should be fully white listed,
requiring us to zero them until they obtain a meaning we support.

Without XSAVE support, all xstate sub-leaves should be zero.

Also move away from checking host XSAVE support - we really ought to
consider the guest flag for that purpose.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
Release-acked-by: Wei Liu <wei.liu2@citrix.com>
---

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 5040a5c864..79abdb692e 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -3433,7 +3433,13 @@ void hvm_cpuid(unsigned int input, unsigned int *eax, unsigned int *ebx,
         *edx = v->vcpu_id * 2;
         break;
 
-    case 0xd:
+    case XSTATE_CPUID:
+        hvm_cpuid(1, NULL, NULL, &_ecx, NULL);
+        if ( !(_ecx & cpufeat_mask(X86_FEATURE_XSAVE)) || count >= 63 )
+        {
+            *eax = *ebx = *ecx = *edx = 0;
+            break;
+        }
         /* EBX value of main leaf 0 depends on enabled xsave features */
         if ( count == 0 && v->arch.xcr0 ) 
         {
diff --git a/xen/arch/x86/traps.c b/xen/arch/x86/traps.c
index 1ef8401b01..5d7232df94 100644
--- a/xen/arch/x86/traps.c
+++ b/xen/arch/x86/traps.c
@@ -928,6 +928,8 @@ void pv_cpuid(struct cpu_user_regs *regs)
 
     switch ( leaf )
     {
+        uint32_t tmp;
+
     case 0x00000001:
         c &= pv_featureset[FEATURESET_1c];
         d &= pv_featureset[FEATURESET_1d];
@@ -1085,14 +1087,19 @@ void pv_cpuid(struct cpu_user_regs *regs)
         break;
 
     case XSTATE_CPUID:
-        if ( !cpu_has_xsave )
+        if ( !((!is_control_domain(currd) && !is_hardware_domain(currd)
+                ? ({
+                    uint32_t ecx;
+
+                    domain_cpuid(currd, 1, 0, &tmp, &tmp, &ecx, &tmp);
+                    ecx & pv_featureset[FEATURESET_1c];
+                  })
+                : cpuid_ecx(1)) & cpufeat_mask(X86_FEATURE_XSAVE)) ||
+             subleaf >= 63 )
             goto unsupported;
         switch ( subleaf )
         {
         case 0:
-        {
-            uint32_t tmp;
-
             /*
              * Always read CPUID.0xD[ECX=0].EBX from hardware, rather than
              * domain policy.  It varies with enabled xstate, and the correct
@@ -1101,7 +1108,6 @@ void pv_cpuid(struct cpu_user_regs *regs)
             if ( !is_control_domain(currd) && !is_hardware_domain(currd) )
                 cpuid_count(leaf, subleaf, &tmp, &b, &tmp, &tmp);
             break;
-        }
 
         case 1:
             a &= pv_featureset[FEATURESET_Da1];