[svsm-devel] [PATCH v3 09/14] virt: sev-guest: Choose the VMPCK key based on executing VMPL
Tom Lendacky
thomas.lendacky at amd.com
Mon Mar 25 23:26:28 CET 2024
Currently, the sev-guest driver uses the vmpck-0 key by default. When an
SVSM is present the kernel is running at a VMPL other than 0 and the
vmpck-0 key is no longer available. So choose the vmpck key based on the
active VMPL level.
Signed-off-by: Tom Lendacky <thomas.lendacky at amd.com>
---
arch/x86/include/asm/sev.h | 2 ++
arch/x86/kernel/sev.c | 6 ++++++
drivers/virt/coco/sev-guest/sev-guest.c | 10 +++++++---
3 files changed, 15 insertions(+), 3 deletions(-)
diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h
index d7be613b7372..066eb0ba3d63 100644
--- a/arch/x86/include/asm/sev.h
+++ b/arch/x86/include/asm/sev.h
@@ -308,6 +308,7 @@ u64 sev_get_status(void);
void kdump_sev_callback(void);
void sev_show_status(void);
void snp_remap_svsm_ca(void);
+int snp_get_vmpl(void);
#else
static inline void sev_es_ist_enter(struct pt_regs *regs) { }
static inline void sev_es_ist_exit(void) { }
@@ -339,6 +340,7 @@ static inline u64 sev_get_status(void) { return 0; }
static inline void kdump_sev_callback(void) { }
static inline void sev_show_status(void) { }
static inline void snp_remap_svsm_ca(void) { }
+static inline int snp_get_vmpl(void) { return 0; }
#endif
#ifdef CONFIG_KVM_AMD_SEV
diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c
index b027b00e315d..7e2b9934a95d 100644
--- a/arch/x86/kernel/sev.c
+++ b/arch/x86/kernel/sev.c
@@ -2464,6 +2464,12 @@ int snp_issue_guest_request(u64 exit_code, struct snp_req_data *input, struct sn
}
EXPORT_SYMBOL_GPL(snp_issue_guest_request);
+int snp_get_vmpl(void)
+{
+ return vmpl;
+}
+EXPORT_SYMBOL_GPL(snp_get_vmpl);
+
static struct platform_device sev_guest_device = {
.name = "sev-guest",
.id = -1,
diff --git a/drivers/virt/coco/sev-guest/sev-guest.c b/drivers/virt/coco/sev-guest/sev-guest.c
index 87f241825bc3..1ff897913bf4 100644
--- a/drivers/virt/coco/sev-guest/sev-guest.c
+++ b/drivers/virt/coco/sev-guest/sev-guest.c
@@ -2,7 +2,7 @@
/*
* AMD Secure Encrypted Virtualization (SEV) guest driver interface
*
- * Copyright (C) 2021 Advanced Micro Devices, Inc.
+ * Copyright (C) 2021-2024 Advanced Micro Devices, Inc.
*
* Author: Brijesh Singh <brijesh.singh at amd.com>
*/
@@ -70,8 +70,8 @@ struct snp_guest_dev {
u8 *vmpck;
};
-static u32 vmpck_id;
-module_param(vmpck_id, uint, 0444);
+static int vmpck_id = -1;
+module_param(vmpck_id, int, 0444);
MODULE_PARM_DESC(vmpck_id, "The VMPCK ID to use when communicating with the PSP.");
/* Mutex to serialize the shared buffer access and command handling. */
@@ -923,6 +923,10 @@ static int __init sev_guest_probe(struct platform_device *pdev)
if (!snp_dev)
goto e_unmap;
+ /* Adjust the default VMPCK key based on the executing VMPL level */
+ if (vmpck_id == -1)
+ vmpck_id = snp_get_vmpl();
+
ret = -EINVAL;
snp_dev->vmpck = get_vmpck(vmpck_id, layout, &snp_dev->os_area_msg_seqno);
if (!snp_dev->vmpck) {
--
2.43.2
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