[PATCH v2 2/3] KVM: x86: fix check legal type of Variable Range MTRRs

Wanpeng Li
2014-08-19T09:02:57Z

The first entry in each pair(IA32_MTRR_PHYSBASEn) defines the base
address and memory type for the range; the second entry(IA32_MTRR_PHYSMASKn)
contains a mask used to determine the address range. The legal values
for the type field of IA32_MTRR_PHYSBASEn are 0,1,4,5, and 6. However,
IA32_MTRR_PHYSMASKn don't have type field. This patch avoid check if
the type field is legal for IA32_MTRR_PHYSMASKn.

Signed-off-by: Wanpeng Li <wanpeng.li@linux.intel.com>
---
v1 -> v2:
* WARN_ON if not fall in variable Range MTRRs
* the base/mask can be separated just with an "&"

arch/x86/kvm/x86.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 5f5edb6..fb3ea7a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -1747,7 +1747,13 @@ static bool mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data)
}

/* variable MTRRs */
- return valid_mtrr_type(data & 0xff);
+ WARN_ON(!(msr >= 0x200 && msr < 0x200 + 2 * KVM_NR_VAR_MTRR));
+
+ if ((msr & 1) == 0)
+ /* MTRR base */
+ return valid_mtrr_type(data & 0xff);
+ /* MTRR mask */
+ return true;
}

static int set_msr_mtrr(struct kvm_vcpu *vcpu, u32 msr, u64 data)
--
1.9.1