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Date: Wed, 14 Dec 2022 13:40:07 -0600
From: Michael Roth <michael.roth@....com>
To: <kvm@...r.kernel.org>
CC: <linux-coco@...ts.linux.dev>, <linux-mm@...ck.org>,
<linux-crypto@...r.kernel.org>, <x86@...nel.org>,
<linux-kernel@...r.kernel.org>, <tglx@...utronix.de>,
<mingo@...hat.com>, <jroedel@...e.de>, <thomas.lendacky@....com>,
<hpa@...or.com>, <ardb@...nel.org>, <pbonzini@...hat.com>,
<seanjc@...gle.com>, <vkuznets@...hat.com>,
<wanpengli@...cent.com>, <jmattson@...gle.com>, <luto@...nel.org>,
<dave.hansen@...ux.intel.com>, <slp@...hat.com>,
<pgonda@...gle.com>, <peterz@...radead.org>,
<srinivas.pandruvada@...ux.intel.com>, <rientjes@...gle.com>,
<dovmurik@...ux.ibm.com>, <tobin@....com>, <bp@...en8.de>,
<vbabka@...e.cz>, <kirill@...temov.name>, <ak@...ux.intel.com>,
<tony.luck@...el.com>, <marcorr@...gle.com>,
<sathyanarayanan.kuppuswamy@...ux.intel.com>,
<alpergun@...gle.com>, <dgilbert@...hat.com>, <jarkko@...nel.org>,
<ashish.kalra@....com>, <harald@...fian.com>,
Brijesh Singh <brijesh.singh@....com>
Subject: [PATCH RFC v7 15/64] x86/sev: Add RMP entry lookup helpers
From: Brijesh Singh <brijesh.singh@....com>
The snp_lookup_rmpentry() 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.
Co-developed-by: Ashish Kalra <ashish.kalra@....com>
Signed-off-by: Ashish Kalra <ashish.kalra@....com>
Signed-off-by: Brijesh Singh <brijesh.singh@....com>
Signed-off-by: Michael Roth <michael.roth@....com>
---
arch/x86/include/asm/sev.h | 4 +-
arch/x86/kernel/sev.c | 83 ++++++++++++++++++++++++++++++++++++++
2 files changed, 86 insertions(+), 1 deletion(-)
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index ebc271bb6d8e..8d3ce2ad27da 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -83,7 +83,7 @@ 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)
#define RMPADJUST_VMSA_PAGE_BIT BIT(16)
/* SNP Guest message request */
@@ -197,6 +197,7 @@ void snp_set_wakeup_secondary_cpu(void);
bool snp_init(struct boot_params *bp);
void __init __noreturn snp_abort(void);
int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, unsigned long *fw_err);
+int snp_lookup_rmpentry(u64 pfn, int *level);
#else
static inline void sev_es_ist_enter(struct pt_regs *regs) { }
static inline void sev_es_ist_exit(void) { }
@@ -221,6 +222,7 @@ static inline int snp_issue_guest_request(u64 exit_code, struct snp_req_data *in
{
return -ENOTTY;
}
+static inline int snp_lookup_rmpentry(u64 pfn, int *level) { return 0; }
#endif
#endif
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 687a91284506..706675561f49 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -61,11 +61,35 @@
#define AP_INIT_CR0_DEFAULT 0x60000010
#define AP_INIT_MXCSR_DEFAULT 0x1f80
+/*
+ * The RMP entry format is not architectural. The format is defined in PPR
+ * Family 19h Model 01h, Rev B1 processor.
+ */
+struct 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;
+} __packed;
+
/*
* The first 16KB from the RMP_BASE is used by the processor for the
* bookkeeping, the range needs 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);
@@ -2440,3 +2464,62 @@ static int __init snp_rmptable_init(void)
* the page(s) used for DMA are hypervisor owned.
*/
fs_initcall(snp_rmptable_init);
+
+static inline unsigned int rmpentry_assigned(struct rmpentry *e)
+{
+ return e->info.assigned;
+}
+
+static inline unsigned int rmpentry_pagesize(struct rmpentry *e)
+{
+ return e->info.pagesize;
+}
+
+static struct rmpentry *rmptable_entry(unsigned long paddr)
+{
+ unsigned long vaddr;
+
+ vaddr = rmptable_start + rmptable_page_offset(paddr);
+ if (unlikely(vaddr > rmptable_end))
+ return ERR_PTR(-EFAULT);
+
+ return (struct rmpentry *)vaddr;
+}
+
+static struct rmpentry *__snp_lookup_rmpentry(u64 pfn, int *level)
+{
+ unsigned long paddr = pfn << PAGE_SHIFT;
+ struct rmpentry *entry, *large_entry;
+
+ if (!cpu_feature_enabled(X86_FEATURE_SEV_SNP))
+ return ERR_PTR(-ENXIO);
+
+ if (!pfn_valid(pfn))
+ return ERR_PTR(-EINVAL);
+
+ entry = rmptable_entry(paddr);
+ if (IS_ERR(entry))
+ return entry;
+
+ /* Read a large RMP entry to get the correct page level used in RMP entry. */
+ large_entry = rmptable_entry(paddr & PMD_MASK);
+ *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);
--
2.25.1
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