On 06/29/2011 05:22 PM, Avi Kivity wrote: > On 06/22/2011 05:36 PM, Xiao Guangrong wrote: >> The idea is from Avi: >> >> | We could cache the result of a miss in an spte by using a reserved bit, and >> | checking the page fault error code (or seeing if we get an ept violation or >> | ept misconfiguration), so if we get repeated mmio on a page, we don't need to >> | search the slot list/tree. >> | (https://lkml.org/lkml/2011/2/22/221) >> >> When the page fault is caused by mmio, we cache the info in the shadow page >> table, and also set the reserved bits in the shadow page table, so if the mmio >> is caused again, we can quickly identify it and emulate it directly >> >> Searching mmio gfn in memslots is heavy since we need to walk all memeslots, it >> can be reduced by this feature, and also avoid walking guest page table for >> soft mmu. >> >> diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c >> index 1319050..e69a47a 100644 >> --- a/arch/x86/kvm/mmu.c >> +++ b/arch/x86/kvm/mmu.c >> @@ -197,6 +197,41 @@ static u64 __read_mostly shadow_x_mask; /* mutual exclusive with nx_mask */ >> static u64 __read_mostly shadow_user_mask; >> static u64 __read_mostly shadow_accessed_mask; >> static u64 __read_mostly shadow_dirty_mask; >> +static u64 __read_mostly shadow_mmio_mask = (0xffull<< 49 | 1ULL); > > One bit is shifted out. And it will fail with 52-bit MAXPHYADDR. > > Please in addition, set the xwr bits to an invalid pattern on EPT (there is an MSR which specifies which patterns are valid; for example execute-only or write-only are invalid). If all patterns are valid AND MAXPHYADDR == 52, then just set the mask to 0 and it the optimization will be disabled. > OK, will fix, thanks! -- 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
