Received-SPF: Pass (protection.outlook.com: domain of amd.com designates
 165.204.84.17 as permitted sender) receiver=protection.outlook.com;
 client-ip=165.204.84.17; helo=SATLEXMB04.amd.com; pr=C
From:   Michael Roth <michael.roth@amd.com>
To:     <kvm@vger.kernel.org>
CC:     <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>, <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>, <jarkko@kernel.org>,
        <ashish.kalra@amd.com>, <nikunj.dadhania@amd.com>,
        Hugh Dickins <hughd@google.com>
Subject: [PATCH RFC v8 18/56] x86/fault: fix handle_split_page_fault() to work with memfd backed pages
Date:   Mon, 20 Feb 2023 12:38:09 -0600
Message-ID: <20230220183847.59159-19-michael.roth@amd.com>
In-Reply-To: <20230220183847.59159-1-michael.roth@amd.com>
References: <20230220183847.59159-1-michael.roth@amd.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Content-Type: text/plain
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Feb 2023 18:46:41.1892
 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: ba5fa676-5082-4d16-0e82-08db1372ce65
X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d
X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com]
X-MS-Exchange-CrossTenant-AuthSource: CY4PEPF0000C966.namprd02.prod.outlook.com
X-MS-Exchange-CrossTenant-AuthAs: Anonymous
X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM4PR12MB5264
Precedence: bulk
List-ID: <linux-crypto.vger.kernel.org>
X-Mailing-List: linux-crypto@vger.kernel.org

From: Hugh Dickins <hughd@google.com>

When the address is backed by a memfd, the code to split the page does
nothing more than remove the PMD from the page tables. So immediately
install a PTE to ensure that any other pages in that 2MB region are
brought back as in 4K pages.

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Ashish Kalra <ashish.kalra@amd.com>
Signed-off-by: Michael Roth <michael.roth@amd.com>
---
 mm/memory.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mm/memory.c b/mm/memory.c
index e68da7e403c6..33c9020ba1f8 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4999,6 +4999,11 @@ static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
 static int handle_split_page_fault(struct vm_fault *vmf)
 {
 	__split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL);
+	/*
+	 * Install a PTE immediately to ensure that any other pages in
+	 * this 2MB region are brought back in as 4K pages.
+	 */
+	__pte_alloc(vmf->vma->vm_mm, vmf->pmd);
 	return 0;
 }
 
-- 
2.25.1