Messages in this thread Patch in this message | | | From | Michael Roth <> | Subject | [PATCH v2] x86/sev: get the AP jump table address from secrets page | Date | Wed, 20 Apr 2022 21:14:45 -0500 |
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From: Brijesh Singh <brijesh.singh@amd.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@amd.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@amd.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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