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[104.155.91.135]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49e69f02e0bsm118285185e9.2.2026.09.13.13.32.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 13 Sep 2026 13:32:39 -0700 (PDT) Date: Sun, 13 Sep 2026 21:32:36 +0100 From: Vincent Donnefort To: sashiko-reviews@lists.linux.dev Cc: kvmarm@lists.linux.dev, Oliver Upton , Marc Zyngier Subject: Re: [PATCH v1] KVM: arm64: Fix protected VMs fault on system with pages larger than 4K Message-ID: References: <20260913173516.3122436-1-vdonnefort@google.com> <20260913175105.A57AC1F000FF@smtp.kernel.org> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260913175105.A57AC1F000FF@smtp.kernel.org> On Sun, Sep 13, 2026 at 05:51:05PM +0000, sashiko-bot@kernel.org wrote: > Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider: > - [High] gmem_abort() passes an unaligned fault_ipa to kvm_pgtable_stage2_map(), which triggers the new -EINVAL check on pKVM hosts. > -- > > commit 724c2b0f8e554f59f7c409467796ff8e9acf590b > Author: Vincent Donnefort > Subject: KVM: arm64: Fix protected VMs fault on system with pages larger than 4K > > This commit aligns the fault IPA down to the page size for protected VMs > in pkvm_mem_abort(), similar to previous fixes for non-protected VMs. > It also adds a strict page-alignment check to pkvm_pgtable_stage2_map() > which returns -EINVAL if the address, size, or physical address are unaligned. > > [ ... ] > > > diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c > > index 8e4c6e4bec123..1ca27d01a3ec6 100644 > > --- a/arch/arm64/kvm/pkvm.c > > +++ b/arch/arm64/kvm/pkvm.c > > @@ -414,6 +414,9 @@ int pkvm_pgtable_stage2_map(struct kvm_pgtable *pgt, u64 addr, u64 size, > > u64 end = addr + size; > > int ret; > > > > + if (!PAGE_ALIGNED(addr | size | phys)) > > + return -EINVAL; > > + > > [Severity: High] > Does this new check break non-protected VMs using guest_memfd on a pKVM host? > > When gmem_abort() handles page faults for guest_memfd slots, it passes > s2fd->fault_ipa directly to kvm_pgtable_stage2_map() without aligning it > down to the page size: > > arch/arm64/kvm/mmu.c:gmem_abort() { > ... > } else { > ret = KVM_PGT_FN(kvm_pgtable_stage2_map)(pgt, s2fd->fault_ipa, > PAGE_SIZE, > __pfn_to_phys(pfn), > prot, memcache, flags); > } > ... > } Ha right... And actually I will do gfn_to_gpa(gfn)... that fits better the series I have sent for the protected VM huge pages. -- Vincent > > Since HPFAR_EL2 only aligns to 4K, on a 16K or 64K page host, the fault_ipa > passed from gmem_abort() will fail this new PAGE_ALIGNED check and return > -EINVAL. This prevents memory mapping and causes the VM fault handling to > abort. > > Should gmem_abort() also be updated to apply ALIGN_DOWN to s2fd->fault_ipa, > just like pkvm_mem_abort() was fixed in this patch? > > > lockdep_assert_held_write(&kvm->mmu_lock); > > mapping = pkvm_mapping_iter_first(&pgt->pkvm_mappings, addr, end - 1); > > -- > Sashiko AI review · https://sashiko.dev/#/patchset/20260913173516.3122436-1-vdonnefort@google.com?part=1