AMD SME claims one bit from physical address to indicate whether the page is encrypted or not. To achieve that we clear out the bit from __PHYSICAL_MASK. The capability to adjust __PHYSICAL_MASK is required beyond AMD SME. For instance for upcoming Intel Multi-Key Total Memory Encryption. Factor it out into a separate feature with own Kconfig handle. It also helps with overhead of AMD SME. It saves more than 3k in .text on defconfig + AMD_MEM_ENCRYPT: add/remove: 3/2 grow/shrink: 5/110 up/down: 189/-3753 (-3564) We would need to return to this once we have infrastructure to patch constants in code. That's good candidate for it. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Reviewed-by: Tom Lendacky <thomas.lendacky@xxxxxxx> --- Previously, I've posted the patch with MKTME patchset, but it's useful on its own as it reduces text size for kernel with AMD_MEM_ENCRYPT enabled. Please consider applying. --- arch/x86/Kconfig | 4 ++++ arch/x86/boot/compressed/kaslr_64.c | 5 +++++ arch/x86/include/asm/page_types.h | 8 +++++++- arch/x86/mm/mem_encrypt_identity.c | 3 +++ arch/x86/mm/pgtable.c | 5 +++++ 5 files changed, 24 insertions(+), 1 deletion(-) diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig index bcdd3e0e2ef5..8e2d0ee0e366 100644 --- a/arch/x86/Kconfig +++ b/arch/x86/Kconfig @@ -333,6 +333,9 @@ config ARCH_SUPPORTS_UPROBES config FIX_EARLYCON_MEM def_bool y +config DYNAMIC_PHYSICAL_MASK + bool + config PGTABLE_LEVELS int default 5 if X86_5LEVEL @@ -1504,6 +1507,7 @@ config ARCH_HAS_MEM_ENCRYPT config AMD_MEM_ENCRYPT bool "AMD Secure Memory Encryption (SME) support" depends on X86_64 && CPU_SUP_AMD + select DYNAMIC_PHYSICAL_MASK ---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/boot/compressed/kaslr_64.c b/arch/x86/boot/compressed/kaslr_64.c index 522d11431433..748456c365f4 100644 --- a/arch/x86/boot/compressed/kaslr_64.c +++ b/arch/x86/boot/compressed/kaslr_64.c @@ -69,6 +69,8 @@ static struct alloc_pgt_data pgt_data; /* The top level page table entry pointer. */ static unsigned long top_level_pgt; +phys_addr_t physical_mask = (1ULL << __PHYSICAL_MASK_SHIFT) - 1; + /* * Mapping information structure passed to kernel_ident_mapping_init(). * Due to relocation, pointers must be assigned at run time not build time. @@ -81,6 +83,9 @@ void initialize_identity_maps(void) /* If running as an SEV guest, the encryption mask is required. */ set_sev_encryption_mask(); + /* Exclude the encryption mask from __PHYSICAL_MASK */ + physical_mask &= ~sme_me_mask; + /* Init mapping_info with run-time function/buffer pointers. */ mapping_info.alloc_pgt_page = alloc_pgt_page; mapping_info.context = &pgt_data; diff --git a/arch/x86/include/asm/page_types.h b/arch/x86/include/asm/page_types.h index 1e53560a84bb..c85e15010f48 100644 --- a/arch/x86/include/asm/page_types.h +++ b/arch/x86/include/asm/page_types.h @@ -17,7 +17,6 @@ #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 __VIRTUAL_MASK ((1UL << __VIRTUAL_MASK_SHIFT) - 1) /* Cast *PAGE_MASK to a signed type so that it is sign-extended if @@ -55,6 +54,13 @@ #ifndef __ASSEMBLY__ +#ifdef CONFIG_DYNAMIC_PHYSICAL_MASK +extern phys_addr_t physical_mask; +#define __PHYSICAL_MASK physical_mask +#else +#define __PHYSICAL_MASK ((phys_addr_t)((1ULL << __PHYSICAL_MASK_SHIFT) - 1)) +#endif + extern int devmem_is_allowed(unsigned long pagenr); extern unsigned long max_low_pfn_mapped; diff --git a/arch/x86/mm/mem_encrypt_identity.c b/arch/x86/mm/mem_encrypt_identity.c index 1b2197d13832..7ae36868aed2 100644 --- a/arch/x86/mm/mem_encrypt_identity.c +++ b/arch/x86/mm/mem_encrypt_identity.c @@ -527,6 +527,7 @@ void __init sme_enable(struct boot_params *bp) /* SEV state cannot be controlled by a command line option */ sme_me_mask = me_mask; sev_enabled = true; + physical_mask &= ~sme_me_mask; return; } @@ -561,4 +562,6 @@ void __init sme_enable(struct boot_params *bp) sme_me_mask = 0; else sme_me_mask = active_by_default ? me_mask : 0; + + physical_mask &= ~sme_me_mask; } diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index 34cda7e0551b..0199b94e6b40 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -7,6 +7,11 @@ #include <asm/fixmap.h> #include <asm/mtrr.h> +#ifdef CONFIG_DYNAMIC_PHYSICAL_MASK +phys_addr_t physical_mask __ro_after_init = (1ULL << __PHYSICAL_MASK_SHIFT) - 1; +EXPORT_SYMBOL(physical_mask); +#endif + #define PGALLOC_GFP (GFP_KERNEL_ACCOUNT | __GFP_ZERO) #ifdef CONFIG_HIGHPTE -- 2.16.3
