[Xen-changelog] [xen stable-4.2] x86/HVM: correct CPUID leaf 80000008 handling

[patchbot@xxxxxxx]

commit 83ed5a882495de9cee915614e30cbb22362061b4
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Wed Apr 9 11:40:09 2014 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Wed Apr 9 11:40:09 2014 +0200

    x86/HVM: correct CPUID leaf 80000008 handling
    
    CPUID[80000008].EAX[23:16] have been given the meaning of the guest
    physical address restriction (in case it needs to be smaller than the
    host's), hence we need to mirror that into vCPUID[80000008].EAX[7:0].
    
    Enforce a lower limit at the same time, as well as a fixed value for
    the virtual address bits, and zero for the guest physical address ones.
    
    In order for the vMTRR code to see these overrides we need to make it
    call hvm_cpuid() instead of domain_cpuid(), which in turn requires
    special casing (and relaxing) the controlling domain.
    
    This additionally should hide an ordering problem in the tools: Both
    xend and xl appear to be restoring a guest from its image before
    setting up the CPUID policy in the hypervisor, resulting in
    domain_cpuid() returning all zeros and hence the check in
    mtrr_var_range_msr_set() failing if the guest previously had more than
    the minimum 36 physical address bits.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Tim Deegan <tim@xxxxxxx>
    master commit: ef437690af8b75e6758dce77af75a22b63982883
    master date: 2014-03-28 13:33:34 +0100
---
 xen/arch/x86/hvm/hvm.c  |   23 ++++++++++++++++++++---
 xen/arch/x86/hvm/mtrr.c |   25 +++++++++++++------------
 2 files changed, 33 insertions(+), 15 deletions(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index d2f8015..ed8ef64 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -2748,6 +2748,8 @@ void hvm_cpuid(unsigned int input, unsigned int *eax, 
unsigned int *ebx,
 
     switch ( input )
     {
+        unsigned int sub_leaf, _eax, _ebx, _ecx, _edx;
+
     case 0x1:
         /* Fix up VLAPIC details. */
         *ebx &= 0x00FFFFFFu;
@@ -2781,8 +2783,6 @@ void hvm_cpuid(unsigned int input, unsigned int *eax, 
unsigned int *ebx,
         *edx = v->vcpu_id * 2;
         break;
     case 0xd:
-    {
-        unsigned int sub_leaf, _eax, _ebx, _ecx, _edx;
         /* EBX value of main leaf 0 depends on enabled xsave features */
         if ( count == 0 && v->arch.xcr0 ) 
         {
@@ -2799,7 +2799,7 @@ void hvm_cpuid(unsigned int input, unsigned int *eax, 
unsigned int *ebx,
             }
         }
         break;
-    }
+
     case 0x80000001:
         /* We expose RDTSCP feature to guest only when
            tsc_mode == TSC_MODE_DEFAULT and host_tsc_is_safe() returns 1 */
@@ -2813,6 +2813,23 @@ void hvm_cpuid(unsigned int input, unsigned int *eax, 
unsigned int *ebx,
         if ( !(hvm_pae_enabled(v) || hvm_long_mode_enabled(v)) )
             *edx &= ~cpufeat_mask(X86_FEATURE_PSE36);
         break;
+
+    case 0x80000008:
+        count = cpuid_eax(0x80000008);
+        count = (count >> 16) & 0xff ?: count & 0xff;
+        if ( (*eax & 0xff) > count )
+            *eax = (*eax & ~0xff) | count;
+
+        hvm_cpuid(1, &_eax, &_ebx, &_ecx, &_edx);
+        count = _edx & (cpufeat_mask(X86_FEATURE_PAE) |
+                        cpufeat_mask(X86_FEATURE_PSE36)) ? 36 : 32;
+        if ( (*eax & 0xff) < count )
+            *eax = (*eax & ~0xff) | count;
+
+        hvm_cpuid(0x80000001, &_eax, &_ebx, &_ecx, &_edx);
+        *eax = (*eax & ~0xffff00) | (_edx & cpufeat_mask(X86_FEATURE_LM)
+                                     ? 0x3000 : 0x2000);
+        break;
     }
 }
 
diff --git a/xen/arch/x86/hvm/mtrr.c b/xen/arch/x86/hvm/mtrr.c
index 1e84e35..a896a5d 100644
--- a/xen/arch/x86/hvm/mtrr.c
+++ b/xen/arch/x86/hvm/mtrr.c
@@ -145,7 +145,7 @@ bool_t is_var_mtrr_overlapped(struct mtrr_state *m)
 
 static int hvm_mtrr_pat_init(void)
 {
-    unsigned int i, j, phys_addr;
+    unsigned int i, j;
 
     memset(&mtrr_epat_tbl, INVALID_MEM_TYPE, sizeof(mtrr_epat_tbl));
     for ( i = 0; i < MTRR_NUM_TYPES; i++ )
@@ -172,11 +172,7 @@ static int hvm_mtrr_pat_init(void)
         }
     }
 
-    phys_addr = 36;
-    if ( cpuid_eax(0x80000000) >= 0x80000008 )
-        phys_addr = (uint8_t)cpuid_eax(0x80000008);
-
-    size_or_mask = ~((1 << (phys_addr - PAGE_SHIFT)) - 1);
+    size_or_mask = ~((1 << (paddr_bits - PAGE_SHIFT)) - 1);
 
     return 0;
 }
@@ -468,16 +464,21 @@ bool_t mtrr_var_range_msr_set(
                     type == 4 || type == 5 || type == 6)) )
         return 0;
 
-    phys_addr = 36;
-    domain_cpuid(d, 0x80000000, 0, &eax, &ebx, &ecx, &edx);
-    if ( eax >= 0x80000008 )
+    if ( d == current->domain )
     {
-        domain_cpuid(d, 0x80000008, 0, &eax, &ebx, &ecx, &edx);
-        phys_addr = (uint8_t)eax;
+        phys_addr = 36;
+        hvm_cpuid(0x80000000, &eax, &ebx, &ecx, &edx);
+        if ( eax >= 0x80000008 )
+        {
+            hvm_cpuid(0x80000008, &eax, &ebx, &ecx, &edx);
+            phys_addr = (uint8_t)eax;
+        }
     }
+    else
+        phys_addr = paddr_bits;
     msr_mask = ~((((uint64_t)1) << phys_addr) - 1);
     msr_mask |= (index & 1) ? 0x7ffUL : 0xf00UL;
-    if ( unlikely(msr_content && (msr_content & msr_mask)) )
+    if ( unlikely(msr_content & msr_mask) )
     {
         HVM_DBG_LOG(DBG_LEVEL_MSR, "invalid msr content:%"PRIx64"\n",
                     msr_content);
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.2

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