linux-kernel - [PATCH v1 2/4] mm: Add poison error check in fixup_user

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Message-ID: <20230920140210.12663-3-ankita@nvidia.com>
Date:   Wed, 20 Sep 2023 19:32:08 +0530
From:   <ankita@...dia.com>
To:     <ankita@...dia.com>, <jgg@...dia.com>,
        <alex.williamson@...hat.com>, <akpm@...ux-foundation.org>,
        <tony.luck@...el.com>, <bp@...en8.de>, <naoya.horiguchi@....com>,
        <linmiaohe@...wei.com>
CC:     <aniketa@...dia.com>, <cjia@...dia.com>, <kwankhede@...dia.com>,
        <targupta@...dia.com>, <vsethi@...dia.com>, <acurrid@...dia.com>,
        <anuaggarwal@...dia.com>, <linux-kernel@...r.kernel.org>,
        <linux-mm@...ck.org>, <linux-edac@...r.kernel.org>,
        <kvm@...r.kernel.org>
Subject: [PATCH v1 2/4] mm: Add poison error check in fixup_user_fault() for mapped pfn

From: Ankit Agrawal <ankita@...dia.com>

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().

Signed-off-by: Ankit Agrawal <ankita@...dia.com>
---
 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 2f8a2d89fde1..fe469326dbe6 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;
 	} else {
-- 
2.17.1