On 06/09/2013 04:59 PM, Gleb Natapov wrote: > On Sun, Jun 09, 2013 at 04:56:42PM +0800, Xiao Guangrong wrote: >> On 06/09/2013 04:45 PM, Gleb Natapov wrote: >>> On Sat, Jun 08, 2013 at 11:15:37AM +0800, Xiao Guangrong wrote: >>>> From: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx> >>>> >>>> Currently, memory synchronization is missed in emulator_fix_hypercall, >>>> please see the commit 758ccc89b83 >>>> (KVM: x86: drop calling kvm_mmu_zap_all in emulator_fix_hypercall) >>>> >>>> This patch fixes it by introducing kvm_vcpus_hang_on_page_start() and >>>> kvm_vcpus_hang_on_page_end which unmap the patched page from guest >>>> and use kvm_flush_remote_tlbs() as the serializing instruction to >>>> ensure the memory coherence >>>> [ The SDM said that INVEPT, INVVPID and MOV (to control register, with >>>> the exception of MOV CR8) are the serializing instructions. ] >>>> >>>> The mmu-lock is held during host patches the page so that it stops vcpus >>>> to fix its further page fault >>>> >>> I have a patch to implement is much simple and in generic way, not >>> relying on MMU internals. >> >> I have considered this way but it seems not simple - it needs a new type of >> request and it forces all vcpus to hang when host is patching the page. >> >> My approach is just reusing the mmu code and requires vcpus to hang only when >> the patched page is bing accessed. > > That's very rare, no point to optimize this code path. Fine to me. I do not have strong opinion on that, please apply your patch instead. ;) -- 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
