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Commit 94d49eb3 authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Thomas Gleixner
Browse files

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: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarTom 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
parent 046c0dbe

arch/x86/Kconfig

+4 −0
Original line number Diff line number Diff line
@@ -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

arch/x86/boot/compressed/kaslr_64.c

+5 −0
Original line number Diff line number Diff line
@@ -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;

arch/x86/include/asm/page_types.h

+7 −1
Original line number Diff line number Diff line
@@ -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;

arch/x86/mm/mem_encrypt_identity.c

+3 −0
Original line number Diff line number Diff line
@@ -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;

}

arch/x86/mm/pgtable.c

+5 −0
Original line number Diff line number Diff line
@@ -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