Il 09/10/2013 18:35, Gleb Natapov ha scritto: > On Wed, Oct 09, 2013 at 06:19:52PM +0200, Paolo Bonzini wrote: >> Il 09/10/2013 18:13, Gleb Natapov ha scritto: >>> 72f857950f6f19 broke shadow on EPT. This patch reverts it and fixes PAE >>> on nEPT (which reverted commit fixed) in other way. >>> >>> Shadow on EPT is now broken because while L1 builds shadow page table >>> for L2 (which is PAE while L2 is in real mode) it never loads L2's >>> GUEST_PDPTR[0-3]. They do not need to be loaded because without nested >>> virtualization HW does this during guest entry if EPT is disabled, >>> but in our case L0 emulates L2's vmentry while EPT is enables, so we >>> cannot rely on vmcs12->guest_pdptr[0-3] to contain up-to-date values >>> and need to re-read PDPTEs from L2 memory. This is what kvm_set_cr3() >>> is doing, but by clearing cache bits during L2 vmentry we drop values >>> that kvm_set_cr3() read from memory. >>> >>> So why the same code does not work for PAE on nEPT? kvm_set_cr3() >>> reads pdptes into vcpu->arch.walk_mmu->pdptrs[]. walk_mmu points to >>> vcpu->arch.nested_mmu while nested guest is running, but ept_load_pdptrs() >>> uses vcpu->arch.mmu which contain incorrect values. Fix that by using >>> walk_mmu in ept_(load|save)_pdptrs. >>> >>> Signed-off-by: Gleb Natapov <gleb@xxxxxxxxxx> >> >> The new fix also looks much more obvious. >> >> Applied to queue, thanks. >> > The patch that break shadow on EPT is in master IIRC, if it is the case > consider this for -rc5. Yes. I would also like to include the PPC patches that Alex pointed to us, but I need a Tested-by because the backport isn't trivial. If it doesn't come soon (i.e. by friday), I'll drop them and include only your patch. Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
