The snp_lookup_page_in_rmptable() can be used by the host to read the RMP entry for a given page. The RMP entry format is documented in AMD PPR, see https://bugzilla.kernel.org/attachment.cgi?id=296015. Signed-off-by: Brijesh Singh <brijesh.singh@xxxxxxx> --- arch/x86/include/asm/sev.h | 4 +-- arch/x86/kernel/sev.c | 26 +++++++++++++++++++ include/linux/sev.h | 51 ++++++++++++++++++++++++++++++++++++++ 3 files changed, 78 insertions(+), 3 deletions(-) create mode 100644 include/linux/sev.h diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index 6c23e694a109..9e7e7e737f55 100644 --- a/arch/x86/include/asm/sev.h +++ b/arch/x86/include/asm/sev.h @@ -9,6 +9,7 @@ #define __ASM_ENCRYPTED_STATE_H #include <linux/types.h> +#include <linux/sev.h> #include <asm/insn.h> #include <asm/sev-common.h> #include <asm/bootparam.h> @@ -75,9 +76,6 @@ extern bool handle_vc_boot_ghcb(struct pt_regs *regs); /* Software defined (when rFlags.CF = 1) */ #define PVALIDATE_FAIL_NOUPDATE 255 -/* RMP page size */ -#define RMP_PG_SIZE_4K 0 - #define RMPADJUST_VMSA_PAGE_BIT BIT(16) #ifdef CONFIG_AMD_MEM_ENCRYPT diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index f9d813d498fa..1aed3d53f59f 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -49,6 +49,8 @@ #define DR7_RESET_VALUE 0x400 #define RMPTABLE_ENTRIES_OFFSET 0x4000 +#define RMPENTRY_SHIFT 8 +#define rmptable_page_offset(x) (RMPTABLE_ENTRIES_OFFSET + (((unsigned long)x) >> RMPENTRY_SHIFT)) /* For early boot hypervisor communication in SEV-ES enabled guests */ static struct ghcb boot_ghcb_page __bss_decrypted __aligned(PAGE_SIZE); @@ -2319,3 +2321,27 @@ static int __init snp_rmptable_init(void) * passthough state, and it is available after subsys_initcall(). */ fs_initcall(snp_rmptable_init); + +struct rmpentry *snp_lookup_page_in_rmptable(struct page *page, int *level) +{ + unsigned long phys = page_to_pfn(page) << PAGE_SHIFT; + struct rmpentry *entry, *large_entry; + unsigned long vaddr; + + if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP)) + return NULL; + + vaddr = rmptable_start + rmptable_page_offset(phys); + if (unlikely(vaddr > rmptable_end)) + return NULL; + + entry = (struct rmpentry *)vaddr; + + /* Read a large RMP entry to get the correct page level used in RMP entry. */ + vaddr = rmptable_start + rmptable_page_offset(phys & PMD_MASK); + large_entry = (struct rmpentry *)vaddr; + *level = RMP_TO_X86_PG_LEVEL(rmpentry_pagesize(large_entry)); + + return entry; +} +EXPORT_SYMBOL_GPL(snp_lookup_page_in_rmptable); diff --git a/include/linux/sev.h b/include/linux/sev.h new file mode 100644 index 000000000000..83c89e999999 --- /dev/null +++ b/include/linux/sev.h @@ -0,0 +1,51 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * AMD Secure Encrypted Virtualization + * + * Author: Brijesh Singh <brijesh.singh@xxxxxxx> + */ + +#ifndef __LINUX_SEV_H +#define __LINUX_SEV_H + +struct __packed rmpentry { + union { + struct { + u64 assigned : 1, + pagesize : 1, + immutable : 1, + rsvd1 : 9, + gpa : 39, + asid : 10, + vmsa : 1, + validated : 1, + rsvd2 : 1; + } info; + u64 low; + }; + u64 high; +}; + +#define rmpentry_assigned(x) ((x)->info.assigned) +#define rmpentry_pagesize(x) ((x)->info.pagesize) +#define rmpentry_vmsa(x) ((x)->info.vmsa) +#define rmpentry_asid(x) ((x)->info.asid) +#define rmpentry_validated(x) ((x)->info.validated) +#define rmpentry_gpa(x) ((unsigned long)(x)->info.gpa) +#define rmpentry_immutable(x) ((x)->info.immutable) + +/* RMP page size */ +#define RMP_PG_SIZE_4K 0 + +#define RMP_TO_X86_PG_LEVEL(level) (((level) == RMP_PG_SIZE_4K) ? PG_LEVEL_4K : PG_LEVEL_2M) + +#ifdef CONFIG_AMD_MEM_ENCRYPT +struct rmpentry *snp_lookup_page_in_rmptable(struct page *page, int *level); +#else +static inline struct rmpentry *snp_lookup_page_in_rmptable(struct page *page, int *level) +{ + return NULL; +} + +#endif /* CONFIG_AMD_MEM_ENCRYPT */ +#endif /* __LINUX_SEV_H */ -- 2.17.1
