AMD SME claims one bit from physical memory address to indicate that the page is encrypted. This bit has to be mask out from __PHYSICAL_MASK.
As an alternative, we can replace __PHYSICAL_MASK with patchable constant and adjust it directly at boot time. Signed-off-by: Kirill A. Shutemov <[email protected]> --- arch/x86/Kconfig | 1 + arch/x86/include/asm/page_types.h | 11 ++++++++++- arch/x86/kernel/patchable_const.c | 3 +++ arch/x86/mm/mem_encrypt.c | 5 +++++ 4 files changed, 19 insertions(+), 1 deletion(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index 78fc28e4f643..2f791aaac1a8 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -1471,6 +1471,7 @@ config ARCH_HAS_MEM_ENCRYPT config AMD_MEM_ENCRYPT bool "AMD Secure Memory Encryption (SME) support" depends on X86_64 && CPU_SUP_AMD + select PATCHABLE_CONST ---help--- Say yes to enable support for the encryption of system memory. This requires an AMD processor that supports Secure Memory diff --git a/arch/x86/include/asm/page_types.h b/arch/x86/include/asm/page_types.h index 1e53560a84bb..8ff82468c9af 100644 --- a/arch/x86/include/asm/page_types.h +++ b/arch/x86/include/asm/page_types.h @@ -5,6 +5,7 @@ #include <linux/const.h> #include <linux/types.h> #include <linux/mem_encrypt.h> +#include <asm/patchable_const.h> /* PAGE_SHIFT determines the page size */ #define PAGE_SHIFT 12 @@ -17,7 +18,8 @@ #define PUD_PAGE_SIZE (_AC(1, UL) << PUD_SHIFT) #define PUD_PAGE_MASK (~(PUD_PAGE_SIZE-1)) -#define __PHYSICAL_MASK ((phys_addr_t)(__sme_clr((1ULL << __PHYSICAL_MASK_SHIFT) - 1))) +#define __PHYSICAL_MASK_DEFAULT ((_AC(1, ULL) << __PHYSICAL_MASK_SHIFT) - 1) + #define __VIRTUAL_MASK ((1UL << __VIRTUAL_MASK_SHIFT) - 1) /* Cast *PAGE_MASK to a signed type so that it is sign-extended if @@ -55,6 +57,13 @@ #ifndef __ASSEMBLY__ +#ifdef CONFIG_AMD_MEM_ENCRYPT +DECLARE_PATCHABLE_CONST_U64(__PHYSICAL_MASK); +#define __PHYSICAL_MASK __PHYSICAL_MASK_READ() +#else +#define __PHYSICAL_MASK ((phys_addr_t)__PHYSICAL_MASK_DEFAULT) +#endif + extern int devmem_is_allowed(unsigned long pagenr); extern unsigned long max_low_pfn_mapped; diff --git a/arch/x86/kernel/patchable_const.c b/arch/x86/kernel/patchable_const.c index d44d91cafee2..8d48c4c101ca 100644 --- a/arch/x86/kernel/patchable_const.c +++ b/arch/x86/kernel/patchable_const.c @@ -89,9 +89,12 @@ int patch_const_u64(unsigned long **start, unsigned long **stop, return -EFAULT; } +PATCHABLE_CONST_U64(__PHYSICAL_MASK); + #ifdef CONFIG_MODULES /* Add an entry for a constant here if it expected to be seen in the modules */ static const struct const_u64_table const_u64_table[] = { + {"__PHYSICAL_MASK", __PHYSICAL_MASK_DEFAULT, &__PHYSICAL_MASK_CURRENT}, }; __init_or_module __nostackprotector diff --git a/arch/x86/mm/mem_encrypt.c b/arch/x86/mm/mem_encrypt.c index 1a53071e2e17..5135b59ce6a5 100644 --- a/arch/x86/mm/mem_encrypt.c +++ b/arch/x86/mm/mem_encrypt.c @@ -1033,4 +1033,9 @@ void __init __nostackprotector sme_enable(struct boot_params *bp) sme_me_mask = 0; else sme_me_mask = active_by_default ? me_mask : 0; + + if (__PHYSICAL_MASK_SET(__PHYSICAL_MASK & ~sme_me_mask)) { + /* Can we handle it? */ + BUG(); + } } -- 2.15.1
