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 | 27 ++++++++++++++++++++++++ arch/x86/kernel/sev.c | 43 ++++++++++++++++++++++++++++++++++++++ include/linux/sev.h | 30 ++++++++++++++++++++++++++ 3 files changed, 100 insertions(+) create mode 100644 include/linux/sev.h diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h index a5f0a1c3ccbe..5b1a6a075c47 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> @@ -77,6 +78,32 @@ extern bool handle_vc_boot_ghcb(struct pt_regs *regs); /* 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) + +/* + * The RMP entry format is not architectural. The format is defined in PPR + * Family 19h Model 01h, Rev B1 processor. + */ +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 RMPADJUST_VMSA_PAGE_BIT BIT(16) diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index 7936c8139c74..f383d2a89263 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -54,6 +54,8 @@ * bookkeeping, the range need to be added during the RMP entry lookup. */ #define RMPTABLE_CPU_BOOKKEEPING_SZ 0x4000 +#define RMPENTRY_SHIFT 8 +#define rmptable_page_offset(x) (RMPTABLE_CPU_BOOKKEEPING_SZ + (((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); @@ -2376,3 +2378,44 @@ static int __init snp_rmptable_init(void) * available after subsys_initcall(). */ fs_initcall(snp_rmptable_init); + +static struct rmpentry *__snp_lookup_rmpentry(u64 pfn, int *level) +{ + unsigned long vaddr, paddr = pfn << PAGE_SHIFT; + struct rmpentry *entry, *large_entry; + + if (!pfn_valid(pfn)) + return ERR_PTR(-EINVAL); + + if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP)) + return ERR_PTR(-ENXIO); + + vaddr = rmptable_start + rmptable_page_offset(paddr); + if (unlikely(vaddr > rmptable_end)) + return ERR_PTR(-ENXIO); + + 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(paddr & PMD_MASK); + large_entry = (struct rmpentry *)vaddr; + *level = RMP_TO_X86_PG_LEVEL(rmpentry_pagesize(large_entry)); + + return entry; +} + +/* + * Return 1 if the RMP entry is assigned, 0 if it exists but is not assigned, + * and -errno if there is no corresponding RMP entry. + */ +int snp_lookup_rmpentry(u64 pfn, int *level) +{ + struct rmpentry *e; + + e = __snp_lookup_rmpentry(pfn, level); + if (IS_ERR(e)) + return PTR_ERR(e); + + return !!rmpentry_assigned(e); +} +EXPORT_SYMBOL_GPL(snp_lookup_rmpentry); diff --git a/include/linux/sev.h b/include/linux/sev.h new file mode 100644 index 000000000000..1a68842789e1 --- /dev/null +++ b/include/linux/sev.h @@ -0,0 +1,30 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * AMD Secure Encrypted Virtualization + * + * Author: Brijesh Singh <brijesh.singh@xxxxxxx> + */ + +#ifndef __LINUX_SEV_H +#define __LINUX_SEV_H + +/* RMUPDATE detected 4K page and 2MB page overlap. */ +#define RMPUPDATE_FAIL_OVERLAP 7 + +#ifdef CONFIG_AMD_MEM_ENCRYPT +int snp_lookup_rmpentry(u64 pfn, int *level); +int psmash(u64 pfn); +int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, int asid, bool immutable); +int rmp_make_shared(u64 pfn, enum pg_level level); +#else +static inline int snp_lookup_rmpentry(u64 pfn, int *level) { return 0; } +static inline int psmash(u64 pfn) { return -ENXIO; } +static inline int rmp_make_private(u64 pfn, u64 gpa, enum pg_level level, int asid, + bool immutable) +{ + return -ENODEV; +} +static inline int rmp_make_shared(u64 pfn, enum pg_level level) { return -ENODEV; } + +#endif /* CONFIG_AMD_MEM_ENCRYPT */ +#endif /* __LINUX_SEV_H */ -- 2.17.1
