From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 488C93B27EA; Sun, 27 Sep 2026 16:26:58 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790526420; cv=none; b=JionWRSdmOVpnN6HhGNQw8Odu3LppShhno9J/dN+D6OXYFsV8wkesEr0y/twA3YAOozo70F7OXG9IqUHtWLtfJHXdkgaqJG/4e/ldlqsbDHSnSWLH40OCOeW0SsxEWT+PZ4dGUetu1OfKfct6qkonsyVMV35123IMZhKyo6XqKI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790526420; c=relaxed/simple; bh=6A5xFIWDpJx3rVrbilD5Zv15HcRr67kq2q2m6q1tNoY=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=fsM/ar3VHzhGVR7CaXACeJOILteNFhEnxFGJCVcISKyQmHHgRt6Ae8lI5QZENBfzGgw0+R2wvDKCRTzg1T2kLYGP4XULe5+EY7wJDgnwTQkpUW101DBMXBAvF7P+SRgDtRb+Aeiobm/vAXDxmWl3FDAQai+RYb5BTwD+Gfwnb9Q= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=kqOdXy5K; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="kqOdXy5K" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C42401F000FF; Sun, 27 Sep 2026 16:26:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790526418; bh=7kW7yGXjKhbeDUHOmR2h0QTxavzpIFMKdj9dx2ZV444=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=kqOdXy5Ke1C4DXMhLh+tKnpi1VA6ACyj2ZCmtln93wuOHC0CZYNXqBC5DcX/HVSUw tcgmukQomsbc2JVRGFIuORep+DRAqGwpuP9jMPA6tmnYol4uLHfhOUmuP3tukUUF4r 0OVKuAliLvavecpPcItmrPAh22SWniGndqa0I3Wcd2Z9Z3RER6HxuPlM26380u+c1G lZ2GLm04mH4CsjPf0kRs6+43lbluRPwtR9gw3+xOhZ16mPGEKSnJUIKccslE4qrBlU 8xnS2a7IdA/Gh/KRBm9VrP1mXGHH4z2vQ71jFe5unBvo2djW+vjsBvVEzyVhpsCLnT tsWxMiqF7tnIA== Received: from sofa.misterjones.org ([185.219.108.64] helo=lobster-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.98.2) (envelope-from ) id 1xAriK-0000000E2Eb-1Xaj; Sun, 27 Sep 2026 16:26:56 +0000 Date: Sun, 27 Sep 2026 17:30:04 +0100 Message-ID: <87qzie3beb.wl-maz@kernel.org> From: Marc Zyngier To: Wei-Lin Chang Cc: Vincent Donnefort , oupton@kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, joey.gouly@arm.com, seiden@linux.ibm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, kernel-team@android.com, fuad.tabba@linux.dev, qperret@google.com, Sashiko , stable@vger.kernel.org Subject: Re: [PATCH v1 5/6] KVM: arm64: Use kvm_s2_fault_vma_info in gmem_abort() In-Reply-To: References: <20260922130821.1666713-1-vdonnefort@google.com> <20260922130821.1666713-6-vdonnefort@google.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: weilin.chang@arm.com, vdonnefort@google.com, oupton@kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, joey.gouly@arm.com, seiden@linux.ibm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, kernel-team@android.com, fuad.tabba@linux.dev, qperret@google.com, sashiko-bot@kernel.org, stable@vger.kernel.org X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Fri, 25 Sep 2026 18:36:42 +0100, Wei-Lin Chang wrote: > > On Tue, Sep 22, 2026 at 02:08:20PM +0100, Vincent Donnefort wrote: > > From: Fuad Tabba > > > > gmem_abort() maps at s2fd->fault_ipa, which HPFAR_EL2 holds at 4K > > granularity whatever the page size. The generic page-table code aligns > > it, but pkvm_pgtable_stage2_map() looks up existing mappings over > > [addr, addr + size), so on a pKVM host with pages larger than 4K a > > guest_memfd-backed guest that faults past the first 4K of a page can > > find its neighbour's mapping, get -EAGAIN and take the same fault > > forever. > > > > Take the addresses from kvm_s2_fault_vma_info instead, as > > user_mem_abort() does, and report the gfn kvm_gmem_get_pfn() failed on > > in the memory fault exit. kvm_s2_fault_get_vma_info() itself isn't > > called: a guest_memfd memslot's userspace_addr doesn't need to be > > backed by a VMA. > > > > Fixes: a7b57e0995927 ("KVM: arm64: Handle guest_memfd-backed guest page faults") > > Reported-by: Sashiko > > Closes: https://lore.kernel.org/r/20260913175105.A57AC1F000FF@smtp.kernel.org > > Cc: stable@vger.kernel.org > > Signed-off-by: Fuad Tabba > > Signed-off-by: Vincent Donnefort > > --- > > arch/arm64/kvm/mmu.c | 28 +++++++++++++--------------- > > 1 file changed, 13 insertions(+), 15 deletions(-) > > > > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c > > index 5aac624b0442..ee0fcca838c1 100644 > > --- a/arch/arm64/kvm/mmu.c > > +++ b/arch/arm64/kvm/mmu.c > > @@ -1953,11 +1953,9 @@ static int gmem_abort(const struct kvm_s2_fault_desc *s2fd) > > enum kvm_pgtable_walk_flags flags = KVM_PGTABLE_WALK_SHARED; > > enum kvm_pgtable_prot prot = KVM_PGTABLE_PROT_R; > > struct kvm_pgtable *pgt = s2fd->vcpu->arch.hw_mmu->pgt; > > - unsigned long mmu_seq; > > - struct page *page; > > + struct kvm_s2_fault_vma_info s2vi = {}; > > I'd say it's unfortunate this struct's name contains vma :P If that was the only thing that is wrong in the MMU code, we'd be in a pretty good position! ;-) > > > struct kvm *kvm = s2fd->vcpu->kvm; > > void *memcache = NULL; > > - kvm_pfn_t pfn; > > gfn_t gfn; > > int ret; > > > > @@ -1968,23 +1966,22 @@ static int gmem_abort(const struct kvm_s2_fault_desc *s2fd) > > return ret; > > } > > > > - if (s2fd->nested) > > - gfn = kvm_s2_trans_output(s2fd->nested) >> PAGE_SHIFT; > > - else > > - gfn = s2fd->fault_ipa >> PAGE_SHIFT; > > + s2vi.vma_pagesize = PAGE_SIZE; > > + s2vi.gfn = ALIGN_DOWN(s2fd->fault_ipa, s2vi.vma_pagesize) >> PAGE_SHIFT; > > + gfn = get_canonical_gfn(s2fd, &s2vi); > > Perhaps it is worth reserving plain "gfn" for the value we use as the > IA of the (shadow) page table, and name this variable something like > canonical_gfn. Similar to what kvm_s2_fault_map() does. Maybe. We have gfn in the vncr fault handling code as well, but that one is the result of a S1 walk, so maybe more obvious. > > > > > write_fault = kvm_is_write_fault(s2fd->vcpu); > > exec_fault = kvm_vcpu_trap_is_exec_fault(s2fd->vcpu); > > > > VM_WARN_ON_ONCE(write_fault && exec_fault); > > > > - mmu_seq = kvm->mmu_invalidate_seq; > > + s2vi.mmu_seq = kvm->mmu_invalidate_seq; > > /* Pairs with the smp_wmb() in kvm_mmu_invalidate_end(). */ > > smp_rmb(); > > > > - ret = kvm_gmem_get_pfn(kvm, s2fd->memslot, gfn, &pfn, &page, NULL); > > + ret = kvm_gmem_get_pfn(kvm, s2fd->memslot, gfn, &s2vi.pfn, &s2vi.page, NULL); > > if (ret) { > > - kvm_prepare_memory_fault_exit(s2fd->vcpu, s2fd->fault_ipa, PAGE_SIZE, > > + kvm_prepare_memory_fault_exit(s2fd->vcpu, gfn_to_gpa(gfn), s2vi.vma_pagesize, > > Huh, I guess you also fixed a bug here? s2fd->fault_ipa could be the > nested ipa instead of the canonical ipa. Yeah, it appears so. Worth capturing in Fixes: as well. M. -- Jazz isn't dead. It just smells funny.