mm: always have io_remap_pfn_range() set pgprot_decrypted()

commit f8f6ae5d077a9bdaf5cbf2ac960a5d1a04b47482 upstream.

The purpose of io_remap_pfn_range() is to map IO memory, such as a
memory mapped IO exposed through a PCI BAR.  IO devices do not
understand encryption, so this memory must always be decrypted.
Automatically call pgprot_decrypted() as part of the generic
implementation.

This fixes a bug where enabling AMD SME causes subsystems, such as RDMA,
using io_remap_pfn_range() to expose BAR pages to user space to fail.
The CPU will encrypt access to those BAR pages instead of passing
unencrypted IO directly to the device.

Places not mapping IO should use remap_pfn_range().

Fixes: aca20d546214 ("x86/mm: Add support to make use of Secure Memory Encryption")
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Tom Lendacky <thomas.lendacky@amd.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brijesh Singh <brijesh.singh@amd.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: "Dave Young" <dyoung@redhat.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Larry Woodman <lwoodman@redhat.com>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Toshimitsu Kani <toshi.kani@hpe.com>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/0-v1-025d64bdf6c4+e-amd_sme_fix_jgg@nvidia.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h
index 0c21014a38f230768b5b40dadffe221d81157e56..cdee1931406190a65994f305e4fd06b4aba1fb05 100644 (file)
--- a/include/asm-generic/pgtable.h
+++ b/include/asm-generic/pgtable.h
@@ -1069,10 +1069,6 @@ static inline bool arch_has_pfn_modify_check(void)
 
 #endif /* !__ASSEMBLY__ */
 
-#ifndef io_remap_pfn_range
-#define io_remap_pfn_range remap_pfn_range
-#endif
-
 #ifndef has_transparent_hugepage
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 #define has_transparent_hugepage() 1

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 156940758fc5cd81b1aba2a776c3e694ad8f6b41..94b138e4c84092922eed9bf7bfcecaa0847bda75 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2422,6 +2422,15 @@ static inline int vm_fault_to_errno(int vm_fault, int foll_flags)
        return 0;
 }
 
+#ifndef io_remap_pfn_range
+static inline int io_remap_pfn_range(struct vm_area_struct *vma,
+                                    unsigned long addr, unsigned long pfn,
+                                    unsigned long size, pgprot_t prot)
+{
+       return remap_pfn_range(vma, addr, pfn, size, pgprot_decrypted(prot));
+}
+#endif
+
 typedef int (*pte_fn_t)(pte_t *pte, pgtable_t token, unsigned long addr,
                        void *data);
 extern int apply_to_page_range(struct mm_struct *mm, unsigned long address,