x86/mm: Decouple dynamic __PHYSICAL_MASK from AMD SME

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@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Cc: linux-mm@kvack.org
Cc: "H. Peter Anvin" <hpa@zytor.com>
Link: https://lkml.kernel.org/r/20180518113028.79825-1-kirill.shutemov@linux.intel.com
This commit is contained in:
Kirill A. Shutemov 2018-05-18 14:30:28 +03:00 committed by Thomas Gleixner
parent 046c0dbec0
commit 94d49eb30e
5 changed files with 24 additions and 1 deletions

View File

@ -337,6 +337,9 @@ 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
@ -1508,6 +1511,7 @@ 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

View File

@ -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;

View File

@ -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;

View File

@ -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;
}

View File

@ -8,6 +8,11 @@
#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