From: Jason Gunthorpe jgg@nvidia.com Subject: mm: always have io_remap_pfn_range() set pgprot_decrypted()

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().

Link: https://lkml.kernel.org/r/0-v1-025d64bdf6c4+e-amd_sme_fix_jgg@nvidia.com Fixes: aca20d546214 ("x86/mm: Add support to make use of Secure Memory Encryption") Signed-off-by: Jason Gunthorpe jgg@nvidia.com Cc: Tom Lendacky thomas.lendacky@amd.com Cc: Thomas Gleixner tglx@linutronix.de CcK Arnd Bergmann arnd@arndb.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 Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

include/linux/mm.h | 9 +++++++++ include/linux/pgtable.h | 4 ---- 2 files changed, 9 insertions(+), 4 deletions(-)

--- a/include/linux/mm.h~mm-always-have-io_remap_pfn_range-set-pgprot_decrypted +++ a/include/linux/mm.h @@ -2759,6 +2759,15 @@ static inline vm_fault_t vmf_insert_page return VM_FAULT_NOPAGE; }

+#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 + static inline vm_fault_t vmf_error(int err) { if (err == -ENOMEM) --- a/include/linux/pgtable.h~mm-always-have-io_remap_pfn_range-set-pgprot_decrypted +++ a/include/linux/pgtable.h @@ -1427,10 +1427,6 @@ typedef unsigned int pgtbl_mod_mask;

#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 _