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Dadhania" Cc: Jarkko Sakkinen , Michael Roth , kvm@vger.kernel.org, linux-coco@lists.linux.dev, linux-mm@kvack.org, linux-crypto@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, jroedel@suse.de, thomas.lendacky@amd.com, hpa@zytor.com, ardb@kernel.org, pbonzini@redhat.com, seanjc@google.com, vkuznets@redhat.com, wanpengli@tencent.com, jmattson@google.com, luto@kernel.org, dave.hansen@linux.intel.com, slp@redhat.com, pgonda@google.com, peterz@infradead.org, srinivas.pandruvada@linux.intel.com, rientjes@google.com, dovmurik@linux.ibm.com, tobin@ibm.com, bp@alien8.de, vbabka@suse.cz, kirill@shutemov.name, ak@linux.intel.com, tony.luck@intel.com, marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com, alpergun@google.com, dgilbert@redhat.com, ashish.kalra@amd.com, harald@profian.com Subject: Re: [PATCH RFC v7 01/64] KVM: Fix memslot boundary condition for large page Message-ID: <20230105081404.GA2257863@chaop.bj.intel.com> Reply-To: Chao Peng References: <20221214194056.161492-1-michael.roth@amd.com> <20221214194056.161492-2-michael.roth@amd.com> <20230105033451.GA2251521@chaop.bj.intel.com> <2ebc9510-d7bf-a46d-6e78-f9e528b79501@amd.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2ebc9510-d7bf-a46d-6e78-f9e528b79501@amd.com> X-Rspam-User: X-Rspamd-Queue-Id: 8B26CC000A X-Rspamd-Server: rspam01 X-Stat-Signature: rpqnxupad85gnbwus1utwbs6itmejuzx X-HE-Tag: 1672906708-169576 X-HE-Meta: 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 > >>> > >>> 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@amd.com/ > > 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 > >>> Signed-off-by: Michael Roth > >>> --- > >>> 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