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Message-ID: <20220421021445.24307-1-michael.roth@amd.com>
Date: Wed, 20 Apr 2022 21:14:45 -0500
From: Michael Roth <michael.roth@....com>
To: <linux-kernel@...r.kernel.org>
CC: Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>, <x86@...nel.org>,
"H . Peter Anvin" <hpa@...or.com>,
Kees Cook <keescook@...omium.org>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
Tony Luck <tony.luck@...el.com>,
"Nick Desaulniers" <ndesaulniers@...gle.com>,
Kuppuswamy Sathyanarayanan
<sathyanarayanan.kuppuswamy@...ux.intel.com>,
Tom Lendacky <thomas.lendacky@....com>,
Venu Busireddy <venu.busireddy@...cle.com>,
"Joerg Roedel" <jroedel@...e.de>,
Tianyu Lan <Tianyu.Lan@...rosoft.com>,
"Brijesh Singh" <brijesh.singh@....com>
Subject: [PATCH v2] x86/sev: get the AP jump table address from secrets page
From: Brijesh Singh <brijesh.singh@....com>
The GHCB specification section 2.7 states that when SEV-SNP is enabled,
a hypervisor must provide the AP jump table physical address through
the SNP secrets pages.
Fixes: 0afb6b660a6b ("x86/sev: Use SEV-SNP AP creation to start secondary CPUs")
Signed-off-by: Brijesh Singh <brijesh.singh@....com>
[ mroth: improve error handling when ioremap()/memremap() return NULL ]
[ mroth: don't mix function calls with declarations ]
Signed-off-by: Michael Roth <michael.roth@....com>
---
v2:
- add handling for memremap()/ioremap() failures (Boris)
- don't mix function calls with declarations (Boris)
arch/x86/include/asm/sev.h | 35 ++++++++++++
arch/x86/kernel/sev.c | 76 ++++++++++++++++++---------
drivers/virt/coco/sevguest/sevguest.h | 35 ------------
3 files changed, 87 insertions(+), 59 deletions(-)
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index 9c2d33f1cfee..509a23c85fe8 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -99,6 +99,41 @@ struct snp_guest_platform_data {
u64 secrets_gpa;
};
+/*
+ * The secrets page contains 96-bytes of reserved field that can be used by
+ * the guest OS. The guest OS uses the area to save the message sequence
+ * number for each VMPCK.
+ *
+ * See the GHCB spec section Secret page layout for the format for this area.
+ */
+struct secrets_os_area {
+ u32 msg_seqno_0;
+ u32 msg_seqno_1;
+ u32 msg_seqno_2;
+ u32 msg_seqno_3;
+ u64 ap_jump_table_pa;
+ u8 rsvd[40];
+ u8 guest_usage[32];
+} __packed;
+
+#define VMPCK_KEY_LEN 32
+
+/* See the SNP spec version 0.9 for secrets page format */
+struct snp_secrets_page_layout {
+ u32 version;
+ u32 imien : 1,
+ rsvd1 : 31;
+ u32 fms;
+ u32 rsvd2;
+ u8 gosvw[16];
+ u8 vmpck0[VMPCK_KEY_LEN];
+ u8 vmpck1[VMPCK_KEY_LEN];
+ u8 vmpck2[VMPCK_KEY_LEN];
+ u8 vmpck3[VMPCK_KEY_LEN];
+ struct secrets_os_area os_area;
+ u8 rsvd3[3840];
+} __packed;
+
#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 f01f4550e2c6..29b832c3f27f 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -558,6 +558,55 @@ void noinstr __sev_es_nmi_complete(void)
__sev_put_ghcb(&state);
}
+static u64 get_secrets_page(void)
+{
+ u64 pa_data = boot_params.cc_blob_address;
+ struct cc_blob_sev_info info;
+ void *map;
+
+ /*
+ * The CC blob contains the address of the secrets page, check if the
+ * blob is present.
+ */
+ if (!pa_data)
+ return 0;
+
+ map = early_memremap(pa_data, sizeof(info));
+ if (!map) {
+ pr_err("Unable to locate SNP secrets page: failed to map the Confidential Computing blob.\n");
+ return 0;
+ }
+ memcpy(&info, map, sizeof(info));
+ early_memunmap(map, sizeof(info));
+
+ /* smoke-test the secrets page passed */
+ if (!info.secrets_phys || info.secrets_len != PAGE_SIZE)
+ return 0;
+
+ return info.secrets_phys;
+}
+
+static u64 get_snp_jump_table_addr(void)
+{
+ struct snp_secrets_page_layout *layout;
+ u64 pa, addr;
+
+ pa = get_secrets_page();
+ if (!pa)
+ return 0;
+
+ layout = (__force void *)ioremap_encrypted(pa, PAGE_SIZE);
+ if (!layout) {
+ pr_err("Unable to locate AP jump table address: failed to map the SNP secrets page.\n");
+ return 0;
+ }
+
+ addr = layout->os_area.ap_jump_table_pa;
+ iounmap(layout);
+
+ return addr;
+}
+
static u64 get_jump_table_addr(void)
{
struct ghcb_state state;
@@ -565,6 +614,9 @@ static u64 get_jump_table_addr(void)
struct ghcb *ghcb;
u64 ret = 0;
+ if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP))
+ return get_snp_jump_table_addr();
+
local_irq_save(flags);
ghcb = __sev_get_ghcb(&state);
@@ -2171,30 +2223,6 @@ static struct platform_device guest_req_device = {
.id = -1,
};
-static u64 get_secrets_page(void)
-{
- u64 pa_data = boot_params.cc_blob_address;
- struct cc_blob_sev_info info;
- void *map;
-
- /*
- * The CC blob contains the address of the secrets page, check if the
- * blob is present.
- */
- if (!pa_data)
- return 0;
-
- map = early_memremap(pa_data, sizeof(info));
- memcpy(&info, map, sizeof(info));
- early_memunmap(map, sizeof(info));
-
- /* smoke-test the secrets page passed */
- if (!info.secrets_phys || info.secrets_len != PAGE_SIZE)
- return 0;
-
- return info.secrets_phys;
-}
-
static int __init snp_init_platform_device(void)
{
struct snp_guest_platform_data data;
diff --git a/drivers/virt/coco/sevguest/sevguest.h b/drivers/virt/coco/sevguest/sevguest.h
index d39bdd013765..21bda26fdb95 100644
--- a/drivers/virt/coco/sevguest/sevguest.h
+++ b/drivers/virt/coco/sevguest/sevguest.h
@@ -60,39 +60,4 @@ struct snp_guest_msg {
u8 payload[4000];
} __packed;
-/*
- * The secrets page contains 96-bytes of reserved field that can be used by
- * the guest OS. The guest OS uses the area to save the message sequence
- * number for each VMPCK.
- *
- * See the GHCB spec section Secret page layout for the format for this area.
- */
-struct secrets_os_area {
- u32 msg_seqno_0;
- u32 msg_seqno_1;
- u32 msg_seqno_2;
- u32 msg_seqno_3;
- u64 ap_jump_table_pa;
- u8 rsvd[40];
- u8 guest_usage[32];
-} __packed;
-
-#define VMPCK_KEY_LEN 32
-
-/* See the SNP spec version 0.9 for secrets page format */
-struct snp_secrets_page_layout {
- u32 version;
- u32 imien : 1,
- rsvd1 : 31;
- u32 fms;
- u32 rsvd2;
- u8 gosvw[16];
- u8 vmpck0[VMPCK_KEY_LEN];
- u8 vmpck1[VMPCK_KEY_LEN];
- u8 vmpck2[VMPCK_KEY_LEN];
- u8 vmpck3[VMPCK_KEY_LEN];
- struct secrets_os_area os_area;
- u8 rsvd3[3840];
-} __packed;
-
#endif /* __VIRT_SEVGUEST_H__ */
--
2.25.1
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