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Subject[PATCH 04/10] KVM: Sanitize cpuid
From: Avi Kivity <avi@redhat.com>

Instead of blacklisting known-unsupported cpuid leaves, whitelist known-
supported leaves. This is more conservative and prevents us from reporting
features we don't support. Also whitelist a few more leaves while at it.

Signed-off-by: Avi Kivity <avi@redhat.com>
Acked-by: Joerg Roedel <joerg.roedel@amd.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
---
arch/x86/kvm/x86.c | 37 +++++++++++++++++++++++++++++++++++--
1 files changed, 35 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 545c61b..f168c61 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -2283,6 +2283,13 @@ static void do_cpuid_1_ent(struct kvm_cpuid_entry2 *entry, u32 function,
entry->flags = 0;
}

+static bool supported_xcr0_bit(unsigned bit)
+{
+ u64 mask = ((u64)1 << bit);
+
+ return mask & (XSTATE_FP | XSTATE_SSE | XSTATE_YMM) & host_xcr0;
+}
+
#define F(x) bit(X86_FEATURE_##x)

static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
@@ -2393,6 +2400,8 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
}
break;
}
+ case 9:
+ break;
case 0xb: {
int i, level_type;

@@ -2414,7 +2423,7 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,

entry->flags |= KVM_CPUID_FLAG_SIGNIFCANT_INDEX;
for (i = 1; *nent < maxnent && i < 64; ++i) {
- if (entry[i].eax == 0)
+ if (entry[i].eax == 0 || !supported_xcr0_bit(i))
continue;
do_cpuid_1_ent(&entry[i], function, i);
entry[i].flags |=
@@ -2451,6 +2460,24 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
entry->ecx &= kvm_supported_word6_x86_features;
cpuid_mask(&entry->ecx, 6);
break;
+ case 0x80000008: {
+ unsigned g_phys_as = (entry->eax >> 16) & 0xff;
+ unsigned virt_as = max((entry->eax >> 8) & 0xff, 48U);
+ unsigned phys_as = entry->eax & 0xff;
+
+ if (!g_phys_as)
+ g_phys_as = phys_as;
+ entry->eax = g_phys_as | (virt_as << 8);
+ entry->ebx = entry->edx = 0;
+ break;
+ }
+ case 0x80000019:
+ entry->ecx = entry->edx = 0;
+ break;
+ case 0x8000001a:
+ break;
+ case 0x8000001d:
+ break;
/*Add support for Centaur's CPUID instruction*/
case 0xC0000000:
/*Just support up to 0xC0000004 now*/
@@ -2460,10 +2487,16 @@ static void do_cpuid_ent(struct kvm_cpuid_entry2 *entry, u32 function,
entry->edx &= kvm_supported_word5_x86_features;
cpuid_mask(&entry->edx, 5);
break;
+ case 3: /* Processor serial number */
+ case 5: /* MONITOR/MWAIT */
+ case 6: /* Thermal management */
+ case 0xA: /* Architectural Performance Monitoring */
+ case 0x80000007: /* Advanced power management */
case 0xC0000002:
case 0xC0000003:
case 0xC0000004:
- /*Now nothing to do, reserved for the future*/
+ default:
+ entry->eax = entry->ebx = entry->ecx = entry->edx = 0;
break;
}

--
1.7.7.1

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