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Message-Id: <20210430123822.13825-7-brijesh.singh@amd.com>
Date: Fri, 30 Apr 2021 07:37:51 -0500
From: Brijesh Singh <brijesh.singh@....com>
To: x86@...nel.org, linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc: tglx@...utronix.de, bp@...en8.de, jroedel@...e.de,
thomas.lendacky@....com, pbonzini@...hat.com, mingo@...hat.com,
dave.hansen@...el.com, rientjes@...gle.com, seanjc@...gle.com,
peterz@...radead.org, hpa@...or.com, tony.luck@...el.com,
Brijesh Singh <brijesh.singh@....com>
Subject: [PATCH Part2 RFC v2 06/37] x86/sev: Add RMP entry lookup helpers
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@....com>
---
arch/x86/include/asm/sev.h | 5 +---
arch/x86/kernel/sev.c | 28 ++++++++++++++++++++
include/linux/sev.h | 54 ++++++++++++++++++++++++++++++++++++++
3 files changed, 83 insertions(+), 4 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 7f4c34dd84e1..a65e78fa3d51 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>
@@ -65,10 +66,6 @@ extern bool handle_vc_boot_ghcb(struct pt_regs *regs);
#define PVALIDATE_FAIL_SIZEMISMATCH 6
#define PVALIDATE_FAIL_NOUPDATE 255 /* Software defined (when rFlags.CF = 1) */
-/* RMP page size */
-#define RMP_PG_SIZE_2M 1
-#define RMP_PG_SIZE_4K 0
-
#ifdef CONFIG_AMD_MEM_ENCRYPT
extern struct static_key_false sev_es_enable_key;
extern void __sev_es_ist_enter(struct pt_regs *regs);
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index 126fa441c0f8..dec4f423e232 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -40,6 +40,10 @@
#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);
@@ -1873,3 +1877,27 @@ static int __init snp_rmptable_init(void)
return 0;
}
early_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..ee038d466786
--- /dev/null
+++ b/include/linux/sev.h
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * AMD Secure Encrypted Virtualization
+ *
+ * Author: Brijesh Singh <brijesh.singh@....com>
+ */
+
+#ifndef __LINUX_SEV_H
+#define __LINUX_SEV_H
+
+struct __packed rmpentry {
+ union {
+ struct {
+ u64 assigned:1;
+ u64 pagesize:1;
+ u64 immutable:1;
+ u64 rsvd1:9;
+ u64 gpa:39;
+ u64 asid:10;
+ u64 vmsa:1;
+ u64 validated:1;
+ u64 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_2M 1
+#define RMP_PG_SIZE_4K 0
+
+/* Macro to convert the x86 page level to the RMP level and vice versa */
+#define X86_TO_RMP_PG_LEVEL(level) (((level) == PG_LEVEL_4K) ? RMP_PG_SIZE_4K : RMP_PG_SIZE_2M)
+#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
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