Messages in this thread | | | Date | Thu, 2 Sep 2010 18:32:20 +0200 | From | "Roedel, Joerg" <> | Subject | Re: [PATCH 1/3] KVM: MMU: Fix 32 bit legacy paging with NPT |
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On Thu, Sep 02, 2010 at 11:56:10AM -0400, Avi Kivity wrote: > On 09/02/2010 06:29 PM, Joerg Roedel wrote: > > This patch fixes 32 bit legacy paging with NPT enabled. The > > mmu_check_root call on the top-level of the loop causes > > root_gfn to take values (in the tdp_enabled path) which are > > outside of guest memory. So the mmu_check_root call fails at > > some point in the loop interation causing the guest to > > tiple-fault. > > This patch changes the mmu_check_root calls to the places > > where they are really necessary. As a side-effect it > > introduces a check for the root of a pae page table too. > > > > > > @@ -2387,6 +2387,10 @@ static int mmu_alloc_roots(struct kvm_vcpu *vcpu) > > return 0; > > } > > direct = !is_paging(vcpu); > > + > > + if (mmu_check_root(vcpu, root_gfn)) > > + return 1; > > + > > for (i = 0; i< 4; ++i) { > > hpa_t root = vcpu->arch.mmu.pae_root[i]; > > > > @@ -2398,10 +2402,10 @@ static int mmu_alloc_roots(struct kvm_vcpu *vcpu) > > continue; > > } > > root_gfn = pdptr>> PAGE_SHIFT; > > + if (mmu_check_root(vcpu, root_gfn)) > > + return 1; > > } else if (vcpu->arch.mmu.root_level == 0) > > root_gfn = 0; > > - if (mmu_check_root(vcpu, root_gfn)) > > - return 1; > > if (tdp_enabled) { > > direct = 1; > > root_gfn = i<< 30; > > The overloading of root_gfn is pretty bad. Also, we don't really need > to check root_gfn for the direct case (the guest can easily switch cr3 > later to one that would fail the check). > > However, I'll apply the patch since it fixes the direct problem. More > involved fixes can come later (esp. after the nnpt patches land).
Ok, great. I will rebase my nnpt patches on-top of this and do some more final testing before I post them.
Thanks,
Joerg
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