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. -- Gleb. -- 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
