linux-kernel - [RFC PATCH 21/47] mm: asi: Add support for locally non-sensitive VM

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Message-Id: <20220223052223.1202152-22-junaids@google.com>
Date:   Tue, 22 Feb 2022 21:21:57 -0800
From:   Junaid Shahid <junaids@...gle.com>
To:     linux-kernel@...r.kernel.org
Cc:     kvm@...r.kernel.org, pbonzini@...hat.com, jmattson@...gle.com,
        pjt@...gle.com, oweisse@...gle.com, alexandre.chartre@...cle.com,
        rppt@...ux.ibm.com, dave.hansen@...ux.intel.com,
        peterz@...radead.org, tglx@...utronix.de, luto@...nel.org,
        linux-mm@...ck.org
Subject: [RFC PATCH 21/47] mm: asi: Add support for locally non-sensitive
 VM_USERMAP pages

VM_USERMAP pages can be mapped into userspace, which would overwrite
the asi_mm field, so we restore that field when freeing these pages.

Signed-off-by: Junaid Shahid <junaids@...gle.com>


---
 mm/vmalloc.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index ea94d8a1e2e9..a89866a926f6 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2424,6 +2424,14 @@ static void asi_unmap_vm_area(struct vm_struct *area)
 	 */
 	if (area->flags & (VM_GLOBAL_NONSENSITIVE | VM_LOCAL_NONSENSITIVE))
 		asi_unmap(area->asi, area->addr, get_vm_area_size(area), true);
+
+	if (area->flags & VM_USERMAP) {
+		uint i;
+
+		for (i = 0; i < area->nr_pages; i++)
+			if (PageLocalNonSensitive(area->pages[i]))
+				area->pages[i]->asi_mm = area->asi->mm;
+	}
 }
 
 #else
-- 
2.35.1.473.g83b2b277ed-goog