From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="noFyjEJv" Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7DDE8A2 for ; Fri, 1 Dec 2023 09:04:53 -0800 (PST) Received: by mail-yb1-xb4a.google.com with SMTP id 3f1490d57ef6-db4004a8aa9so948034276.1 for ; Fri, 01 Dec 2023 09:04:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1701450292; x=1702055092; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=YbmCSI5K+Qp+wla/FUZNboDkH6vkaCc9VLdnolKakNc=; b=noFyjEJvzmVlRRLojlSuZXrCrc4Yzgu+xDbrsD/cVPN7F03GE6eMPPp2H+YzBE1dwq R+pO5gCtR8CSLpl9WZGog5pt0o+51OULhEANXl1ORn/9U3Ib3uS4kVhhHjjw+QRjnlQb iTobRKJhTmdnsnzXNvxcmnEVfBYI6g+xvpIe+Tn2XX1MxywHY4ZVtrqQmbs1EYx5S3XX 25t/M24RG29rgjcLg+dXhKtukBHzNIg4uz4B7MlaSLZ9EvMhB+pajfNMychzXyjUsg3/ fjgGd5Uu1js1Yj+iyPEA6TCAsGuHPdGgKVVNnpCKBgBMYuBiIll9KqM5lW05R0huS1IL COgQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1701450292; x=1702055092; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=YbmCSI5K+Qp+wla/FUZNboDkH6vkaCc9VLdnolKakNc=; b=mMFS+RIPh18isvkrTO+aRT1R8LQUt6K5tFh++MCL3mvQ0jQDp3JOvwK5wOdVhJTZQQ Ggwj/qIaU8Y5MjNSm75P2utkAyoOy463Avt9mxWv2W2uec530wKJCLOHrYgUuy9s5agG faNpCxZ5zwwSGhOZ93nB0Pe/rM4OfZc+FszCoBIfG0d2NASr0fmO14VFjNdsPyEetxdQ GEDeSNThYVxh2pvejFgC/uapXpQynpsxF8Zq+2G0S/lRcHRLblVX/sQxKGtPqJdptv1p 7vnkRiP76Ca36hi2PFIllZA/BcD0qC1w3cc6JuP+0DvgoETwyhaMCqw5+UivvBRz3BPB 2oLA== X-Gm-Message-State: AOJu0YwGiO2KfN+vaJTLRekiATiGstGfnSCeCuNvOPRzQuRfCcWJ0qGc TkIRzr17soHbgbqcWZLMqWqu+QPtNvo= X-Google-Smtp-Source: AGHT+IEa3BfWc92nmp+AtwxI8x7qhWNabfXhEQhxlZ9l+TV5/mqVnAJW8EBvcmW340xIWHXBNkD9Ysp+RPg= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a25:6e83:0:b0:d9a:e3d9:99bd with SMTP id j125-20020a256e83000000b00d9ae3d999bdmr780648ybc.5.1701450292702; Fri, 01 Dec 2023 09:04:52 -0800 (PST) Date: Fri, 1 Dec 2023 09:04:51 -0800 In-Reply-To: <20231123003513.24292-3-ankita@nvidia.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20231123003513.24292-1-ankita@nvidia.com> <20231123003513.24292-3-ankita@nvidia.com> Message-ID: Subject: Re: [PATCH v2 2/4] mm: Add poison error check in fixup_user_fault() for mapped pfn From: Sean Christopherson To: ankita@nvidia.com Cc: jgg@nvidia.com, alex.williamson@redhat.com, naoya.horiguchi@nec.com, akpm@linux-foundation.org, tony.luck@intel.com, bp@alien8.de, linmiaohe@huawei.com, rafael@kernel.org, lenb@kernel.org, james.morse@arm.com, shiju.jose@huawei.com, bhelgaas@google.com, pabeni@redhat.com, yishaih@nvidia.com, shameerali.kolothum.thodi@huawei.com, kevin.tian@intel.com, aniketa@nvidia.com, cjia@nvidia.com, kwankhede@nvidia.com, targupta@nvidia.com, vsethi@nvidia.com, acurrid@nvidia.com, apopple@nvidia.com, anuaggarwal@nvidia.com, jhubbard@nvidia.com, danw@nvidia.com, mochs@nvidia.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, linux-edac@vger.kernel.org, linux-acpi@vger.kernel.org Content-Type: text/plain; charset="us-ascii" On Thu, Nov 23, 2023, ankita@nvidia.com wrote: > From: Ankit Agrawal > > The fixup_user_fault() currently does not expect a VM_FAULT_HWPOISON > and hence does not check for it while calling vm_fault_to_errno(). Since > we now have a new code path which can trigger such case, change > fixup_user_fault to look for VM_FAULT_HWPOISON. > > Also make hva_to_pfn_remapped check for -EHWPOISON and communicate the > poison fault up to the user_mem_abort(). I would much prefer the KVM change be split out to its own patch, I see no reason why it needs to be bundled with the fixup_user_fault() change. KVM will set pfn to KVM_PFN_ERR_FAULT before and after the fixup_user_fault() change. > Signed-off-by: Ankit Agrawal > --- > mm/gup.c | 2 +- > virt/kvm/kvm_main.c | 6 ++++++ > 2 files changed, 7 insertions(+), 1 deletion(-) > > diff --git a/mm/gup.c b/mm/gup.c > index 231711efa390..b78af20a0f52 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -1414,7 +1414,7 @@ int fixup_user_fault(struct mm_struct *mm, > } > > if (ret & VM_FAULT_ERROR) { > - int err = vm_fault_to_errno(ret, 0); > + int err = vm_fault_to_errno(ret, FOLL_HWPOISON); > > if (err) > return err; > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 486800a7024b..2ff067f21a7c 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -2731,6 +2731,12 @@ kvm_pfn_t hva_to_pfn(unsigned long addr, bool atomic, bool interruptible, > r = hva_to_pfn_remapped(vma, addr, write_fault, writable, &pfn); > if (r == -EAGAIN) > goto retry; > + > + if (r == -EHWPOISON) { > + pfn = KVM_PFN_ERR_HWPOISON; > + goto exit; > + } > + > if (r < 0) > pfn = KVM_PFN_ERR_FAULT; I vote for if (r == -EHWPOISON) pfn = KVM_PFN_ERR_HWPOISON; else if (r < 0) pfn = KVM_PFN_ERR_FAULT; or even opportunstically fix the < 0 weirdness: if (r == -EHWPOISON) pfn = KVM_PFN_ERR_HWPOISON; else if (r) pfn = KVM_PFN_ERR_FAULT; It's rather confusing to see a goto in one error path but an effective fallthrough in a different error path, i.e. gives the impression that KVM_PFN_ERR_HWPOISON has some special behavior that doesn't apply to KVM_PFN_ERR_FAULT.