The patch titled
Subject: efi/unaccepted: do not let /proc/vmcore try to access unaccepted memory
has been added to the -mm mm-unstable branch. Its filename is
efi-unaccepted-do-not-let-proc-vmcore-try-to-access-unaccepted-memory.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/efi-unaccepted-do-not-let-proc-vmcore-try-to-access-unaccepted-memory.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Subject: efi/unaccepted: do not let /proc/vmcore try to access unaccepted memory
Date: Mon, 11 Sep 2023 14:21:13 +0300
Patch series "Do not try to access unaccepted memory", v2.
Support for unaccepted memory was added recently, refer commit
dcdfdd40fa82 ("mm: Add support for unaccepted memory"), whereby
a virtual machine may need to accept memory before it can be used.
Plug a few gaps where RAM is exposed without checking if it is
unaccepted memory.
This patch (of 2):
Support for unaccepted memory was added recently, refer commit
dcdfdd40fa82 ("mm: Add support for unaccepted memory"), whereby a virtual
machine may need to accept memory before it can be used.
Do not let /proc/vmcore try to access unaccepted memory because it can
cause the guest to fail.
For /proc/vmcore, which is read-only, this means a read or mmap of
unaccepted memory will return zeros.
Link: https://lkml.kernel.org/r/20230911112114.91323-1-adrian.hunter@xxxxxxxxx
Link: https://lkml.kernel.org/r/20230911112114.91323-2-adrian.hunter@xxxxxxxxx
Signed-off-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Dave Young <dyoung@xxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Cc: Mike Rapoport <rppt@xxxxxxxxxxxxx>
Cc: Tom Lendacky <thomas.lendacky@xxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/firmware/efi/unaccepted_memory.c | 20 ++++++++++++++++++++
include/linux/mm.h | 7 +++++++
2 files changed, 27 insertions(+)
--- a/drivers/firmware/efi/unaccepted_memory.c~efi-unaccepted-do-not-let-proc-vmcore-try-to-access-unaccepted-memory
+++ a/drivers/firmware/efi/unaccepted_memory.c
@@ -3,6 +3,7 @@
#include <linux/efi.h>
#include <linux/memblock.h>
#include <linux/spinlock.h>
+#include <linux/crash_dump.h>
#include <asm/unaccepted_memory.h>
/* Protects unaccepted memory bitmap */
@@ -145,3 +146,22 @@ bool range_contains_unaccepted_memory(ph
return ret;
}
+
+#ifdef CONFIG_PROC_VMCORE
+static bool unaccepted_memory_vmcore_pfn_is_ram(struct vmcore_cb *cb,
+ unsigned long pfn)
+{
+ return !pfn_is_unaccepted_memory(pfn);
+}
+
+static struct vmcore_cb vmcore_cb = {
+ .pfn_is_ram = unaccepted_memory_vmcore_pfn_is_ram,
+};
+
+static int __init unaccepted_memory_init_kdump(void)
+{
+ register_vmcore_cb(&vmcore_cb);
+ return 0;
+}
+core_initcall(unaccepted_memory_init_kdump);
+#endif /* CONFIG_PROC_VMCORE */
--- a/include/linux/mm.h~efi-unaccepted-do-not-let-proc-vmcore-try-to-access-unaccepted-memory
+++ a/include/linux/mm.h
@@ -4055,4 +4055,11 @@ static inline void accept_memory(phys_ad
#endif
+static inline bool pfn_is_unaccepted_memory(unsigned long pfn)
+{
+ phys_addr_t paddr = pfn << PAGE_SHIFT;
+
+ return range_contains_unaccepted_memory(paddr, paddr + PAGE_SIZE);
+}
+
#endif /* _LINUX_MM_H */
_
Patches currently in -mm which might be from adrian.hunter@xxxxxxxxx are
efi-unaccepted-do-not-let-proc-vmcore-try-to-access-unaccepted-memory.patch
proc-kcore-do-not-try-to-access-unaccepted-memory.patch
