On Mon, Jun 20, 2022 at 4:02 PM Ashish Kalra <Ashish.Kalra@xxxxxxx> wrote: > > From: Brijesh Singh <brijesh.singh@xxxxxxx> > > 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 9c2d33f1cfee..cb16f0e5b585 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> > @@ -84,6 +85,32 @@ 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 25c7feb367f6..59e7ec6b0326 100644 > --- a/arch/x86/kernel/sev.c > +++ b/arch/x86/kernel/sev.c > @@ -65,6 +65,8 @@ > * 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); > @@ -2386,3 +2388,44 @@ 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); nit: I think we should check if SNP is enabled first, before doing anything else. In other words, I think we should move this check above the `!pfn_valid()` check. > + > + vaddr = rmptable_start + rmptable_page_offset(paddr); > + if (unlikely(vaddr > rmptable_end)) > + return ERR_PTR(-ENXIO); nit: It would be nice to use a different error code here, from the SNP feature check. That way, if this function fails, it's easier to diagnose where the function failed from the error code. > + > + 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); nit: I think the declarations for `psmash()`, `rmp_make_private()`, and `rmp_make_shared()` should be introduced in the patches that have their definitions. > +#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 */ > -- > 2.25.1 >
