On Thu, Jan 05, 2023 at 09:38:59AM +0530, Nikunj A. Dadhania wrote: > > > On 05/01/23 09:04, Chao Peng wrote: > > On Wed, Jan 04, 2023 at 12:01:05PM +0000, Jarkko Sakkinen wrote: > >> On Wed, Dec 14, 2022 at 01:39:53PM -0600, Michael Roth wrote: > >>> From: Nikunj A Dadhania <nikunj@xxxxxxx> > >>> > >>> Aligned end boundary causes a kvm crash, handle the case. > >>> > >> > >> Link: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Flore.kernel.org%2Fkvm%2F20221202061347.1070246-8-chao.p.peng%40linux.intel.com%2F&data=05%7C01%7Cnikunj.dadhania%40amd.com%7C7a95933fac1b433e339c08daeece6c2c%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C638084867591405299%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=vDEu9Uxs0QRdzbUkJbE2LsJnMHJJHBdQijkePbE2woc%3D&reserved=0 > >> > >> Chao, are you aware of this issue already? > > > > Thanks Jarkko adding me. I'm not aware of there is a fix. > > It was discussed here: https://lore.kernel.org/all/e234d307-0b05-6548-5882-c24fc32c8e77@xxxxxxx/ > > I was hitting this with one of the selftests case. Yeah, I remember that discussion. With the new UPM code, this bug should be fixed. If you still hit the issue please let me know. Thanks, Chao > > > > >> > >>> Signed-off-by: Nikunj A Dadhania <nikunj@xxxxxxx> > >>> Signed-off-by: Michael Roth <michael.roth@xxxxxxx> > >>> --- > >>> arch/x86/kvm/mmu/mmu.c | 3 +++ > >>> 1 file changed, 3 insertions(+) > >>> > >>> diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c > >>> index b1953ebc012e..b3ffc61c668c 100644 > >>> --- a/arch/x86/kvm/mmu/mmu.c > >>> +++ b/arch/x86/kvm/mmu/mmu.c > >>> @@ -7159,6 +7159,9 @@ static void kvm_update_lpage_private_shared_mixed(struct kvm *kvm, > >>> for (gfn = first + pages; gfn < last; gfn += pages) > >>> linfo_set_mixed(gfn, slot, level, false); > >>> > >>> + if (gfn == last) > >>> + goto out; > >>> + > > > > Nikunj or Michael, could you help me understand in which case it causes > > a KVM crash? To me, even the end is aligned to huge page boundary, but: > > last = (end - 1) & mask; > > so 'last' is the base address for the last effective huage page. Even > > when gfn == last, it should still a valid page and needs to be updated > > for mem_attrs, correct? > > Yes, that is correct with: last = (end - 1) & mask; > > We can drop this patch from SNP series. > > Regards > Nikunj
