On Thu, Jun 18, 2009 at 10:39:32AM +0800, Yang, Sheng wrote:
> On Tuesday 16 June 2009 20:05:29 Marcelo Tosatti wrote:
> > Do not allow invalid MTRR/PAT values in set_msr_mtrr.
> >
> > Please review carefully.
> >
> > Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
> >
> Looks fine to me.
>
> Is it necessary to check reserved bit of MSR_MTRRdefType and variable MTRRs as
> well? Maybe like this:
>
> if (msr == MSR_MTRRdefType) {
> return valid_mtrr_type(data & ~0xc00ull);
> }
>
> And variable ones can be:
>
> #define MTRR_VALID_MASK(v, msr) (~(rsvd_bits(cpuid_max_physaddr(v)) | ((msr %
> 2) << 11)))
>
> return valid_mtrr_type(data & MTRR_VALID_MASK(vcpu, msr)))
>
>
> (rsvd_bits() is in mmu.c, both untested)
>
> Maybe we can put cpuid_max_physaddr as a field in vcpu struct?
Sheng,
This in the BIOS is writing 1's into the reserved address bits into
variable MTRR:
wrmsr_smp(MTRRphysMask_MSR(0), ~(0x20000000ull - 1) | 0x800);
So i'll leave just memory type validity checking and MSR_MTRRdefType
valid bit checks in for now:
KVM: x86: verify MTRR/PAT validity
Do not allow invalid memory types in MTRR/PAT (generating a #GP
otherwise).
Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Index: kvm/arch/x86/kvm/x86.c
===================================================================
--- kvm.orig/arch/x86/kvm/x86.c
+++ kvm/arch/x86/kvm/x86.c
@@ -721,11 +721,48 @@ static bool msr_mtrr_valid(unsigned msr)
return false;
}
+static bool valid_pat_type(unsigned t)
+{
+ return t < 8 && (1 << t) & 0xf3; /* 0, 1, 4, 5, 6, 7 */
+}
+
+static bool valid_mtrr_type(unsigned t)
+{
+ return t < 8 && (1 << t) & 0x73; /* 0, 1, 4, 5, 6 */
+}
+
+static bool mtrr_valid(struct kvm_vcpu *vcpu, u32 msr, u64 data)
+{
+ int i;
+
+ if (!msr_mtrr_valid(msr))
+ return false;
+
+ if (msr == MSR_IA32_CR_PAT) {
+ for (i = 0; i < 8; i++)
+ if (!valid_pat_type((data >> (i * 8)) & 0xff))
+ return false;
+ return true;
+ } else if (msr == MSR_MTRRdefType) {
+ if (data & ~0xcff)
+ return false;
+ return valid_mtrr_type(data & 0xff);
+ } else if (msr >= MSR_MTRRfix64K_00000 && msr <= MSR_MTRRfix4K_F8000) {
+ for (i = 0; i < 8 ; i++)
+ if (!valid_mtrr_type((data >> (i * 8)) & 0xff))
+ return false;
+ return true;
+ }
+
+ /* variable MTRRs */
+ return valid_mtrr_type(data & 0xff);
+}
+
static int set_msr_mtrr(struct kvm_vcpu *vcpu, u32 msr, u64 data)
{
u64 *p = (u64 *)&vcpu->arch.mtrr_state.fixed_ranges;
- if (!msr_mtrr_valid(msr))
+ if (!mtrr_valid(vcpu, msr, data))
return 1;
if (msr == MSR_MTRRdefType) {
--
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