linux-kernel - [PATCH 04/10] KVM: Sanitize cpuid

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Date:	Fri, 02 Dec 2011 20:46:45 -0500
From:	Steven Rostedt <rostedt@...dmis.org>
To:	linux-kernel@...r.kernel.org,
	linux-rt-users <linux-rt-users@...r.kernel.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Carsten Emde <C.Emde@...dl.org>,
	John Kacur <jkacur@...hat.com>, Avi Kivity <avi@...hat.com>,
	Joerg Roedel <joerg.roedel@....com>,
	Marcelo Tosatti <mtosatti@...hat.com>
Subject: [PATCH 04/10] KVM: Sanitize cpuid

From: Avi Kivity <avi@...hat.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@...hat.com>
Acked-by: Joerg Roedel <joerg.roedel@....com>
Signed-off-by: Marcelo Tosatti <mtosatti@...hat.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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