Messages in this thread | | | Subject | Re: [PATCH v1 1/4] KVM: MMU: check guest CR3 reserved bits based on its physical address width. | From | Paolo Bonzini <> | Date | Mon, 14 Aug 2017 18:40:17 +0200 |
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On 14/08/2017 18:13, Jim Mattson wrote: >> ctxt->ops->get_msr(ctxt, MSR_EFER, &efer); >> - if (efer & EFER_LMA) >> - rsvd = CR3_L_MODE_RESERVED_BITS & ~CR3_PCID_INVD; >> + if (efer & EFER_LMA) { >> + u64 maxphyaddr; >> + u32 eax = 0x80000008; >> + >> + ctxt->ops->get_cpuid(ctxt, &eax, NULL, NULL, NULL); >> + maxphyaddr = eax * 0xff; > > What if leaf 0x80000008 is not defined?
I noticed this too, but I thought it was mitigated by being under EFER_LMA. Unfortunately, kvm_set_efer doesn't check guest_cpuid_has_longmode, so I guess you do have to test leaf 0x80000000 first. Alternatively:
1) kvm_cpuid could return false if it's falling back to check_cpuid_limit, and emulator_get_cpuid can then be changed to return bool
2) kvm_cpuid and emulator_get_cpuid could gain a new argument to disable the check_cpuid_limit fallback.
Yu, would you like to implement the latter?
Paolo
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