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Thu, 28 Aug 2025 03:22:45 -0700 (PDT) Date: Thu, 28 Aug 2025 12:22:12 +0200 In-Reply-To: <20250828102202.1849035-24-ardb+git@google.com> Precedence: bulk X-Mailing-List: linux-efi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250828102202.1849035-24-ardb+git@google.com> X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-Developer-Signature: v=1; a=openpgp-sha256; l=5360; i=ardb@kernel.org; h=from:subject; bh=C0q1ad84KjlSQtQ9LCyoiSGw3tyN88QelZe45Gf2aZQ=; b=owGbwMvMwCVmkMcZplerG8N4Wi2JIWOD7tWZ1t0um3+FGXO27vN0sQywvJAWl7qi+tFvpc5a7 q3N7R4dpSwMYlwMsmKKLAKz/77beXqiVK3zLFmYOaxMIEMYuDgFYCKaqgz/Ey9vmrmW99ze48sS 4++9m1k4bffn+S8XNbkd27ks/+5UzWsM/+sf6Rhf05EUTWdzD5p3P9tE8Y5RWuK58zdmMvy+8YF RnB0A X-Mailer: git-send-email 2.51.0.268.g9569e192d0-goog Message-ID: <20250828102202.1849035-33-ardb+git@google.com> Subject: [PATCH v7 09/22] x86/sev: Use boot SVSM CA for all startup and init code From: Ard Biesheuvel To: linux-kernel@vger.kernel.org Cc: linux-efi@vger.kernel.org, x86@kernel.org, Ard Biesheuvel , Borislav Petkov , Ingo Molnar , Kevin Loughlin , Tom Lendacky , Josh Poimboeuf , Peter Zijlstra , Nikunj A Dadhania Content-Type: text/plain; charset="UTF-8" From: Ard Biesheuvel To avoid having to reason about whether or not to use the per-CPU SVSM calling area when running startup and init code on the boot CPU, reuse the boot SVSM calling area as the per-CPU area for CPU #0. This removes the need to make the per-CPU variables and associated state in sev_cfg accessible to the startup code once confined. Signed-off-by: Ard Biesheuvel --- arch/x86/boot/compressed/sev.c | 13 ------ arch/x86/boot/startup/sev-startup.c | 11 ++--- arch/x86/coco/sev/core.c | 47 +++++++++----------- arch/x86/include/asm/sev-internal.h | 16 ------- 4 files changed, 28 insertions(+), 59 deletions(-) diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c index dffe607e6d8b..de73da526577 100644 --- a/arch/x86/boot/compressed/sev.c +++ b/arch/x86/boot/compressed/sev.c @@ -37,19 +37,6 @@ struct ghcb *boot_ghcb; #define __BOOT_COMPRESSED -extern u64 boot_svsm_caa_pa; - -struct svsm_ca *svsm_get_caa(void) -{ - /* The decompressor is mapped 1:1 so VA == PA */ - return (struct svsm_ca *)boot_svsm_caa_pa; -} - -u64 svsm_get_caa_pa(void) -{ - return boot_svsm_caa_pa; -} - u8 snp_vmpl; /* Include code for early handlers */ diff --git a/arch/x86/boot/startup/sev-startup.c b/arch/x86/boot/startup/sev-startup.c index 8009a37d53c1..b0fc63f8dee1 100644 --- a/arch/x86/boot/startup/sev-startup.c +++ b/arch/x86/boot/startup/sev-startup.c @@ -50,9 +50,6 @@ u64 sev_secrets_pa __ro_after_init; /* For early boot SVSM communication */ struct svsm_ca boot_svsm_ca_page __aligned(PAGE_SIZE); -DEFINE_PER_CPU(struct svsm_ca *, svsm_caa); -DEFINE_PER_CPU(u64, svsm_caa_pa); - /* * Nothing shall interrupt this code path while holding the per-CPU * GHCB. The backup GHCB is only for NMIs interrupting this path. @@ -153,7 +150,9 @@ void __head early_snp_set_memory_private(unsigned long vaddr, unsigned long padd unsigned long npages) { struct psc_desc d = { - SNP_PAGE_STATE_PRIVATE, svsm_get_caa(), svsm_get_caa_pa() + SNP_PAGE_STATE_PRIVATE, + rip_rel_ptr(&boot_svsm_ca_page), + boot_svsm_caa_pa }; /* @@ -176,7 +175,9 @@ void __head early_snp_set_memory_shared(unsigned long vaddr, unsigned long paddr unsigned long npages) { struct psc_desc d = { - SNP_PAGE_STATE_SHARED, svsm_get_caa(), svsm_get_caa_pa() + SNP_PAGE_STATE_SHARED, + rip_rel_ptr(&boot_svsm_ca_page), + boot_svsm_caa_pa }; /* diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c index a833b2b31d3d..9782ebe30675 100644 --- a/arch/x86/coco/sev/core.c +++ b/arch/x86/coco/sev/core.c @@ -46,6 +46,25 @@ #include #include +DEFINE_PER_CPU(struct svsm_ca *, svsm_caa); +DEFINE_PER_CPU(u64, svsm_caa_pa); + +static inline struct svsm_ca *svsm_get_caa(void) +{ + if (sev_cfg.use_cas) + return this_cpu_read(svsm_caa); + else + return rip_rel_ptr(&boot_svsm_ca_page); +} + +static inline u64 svsm_get_caa_pa(void) +{ + if (sev_cfg.use_cas) + return this_cpu_read(svsm_caa_pa); + else + return boot_svsm_caa_pa; +} + /* AP INIT values as documented in the APM2 section "Processor Initialization State" */ #define AP_INIT_CS_LIMIT 0xffff #define AP_INIT_DS_LIMIT 0xffff @@ -1312,7 +1331,8 @@ static void __init alloc_runtime_data(int cpu) struct svsm_ca *caa; /* Allocate the SVSM CA page if an SVSM is present */ - caa = memblock_alloc_or_panic(sizeof(*caa), PAGE_SIZE); + caa = cpu ? memblock_alloc_or_panic(sizeof(*caa), PAGE_SIZE) + : &boot_svsm_ca_page; per_cpu(svsm_caa, cpu) = caa; per_cpu(svsm_caa_pa, cpu) = __pa(caa); @@ -1366,32 +1386,9 @@ void __init sev_es_init_vc_handling(void) init_ghcb(cpu); } - /* If running under an SVSM, switch to the per-cpu CA */ - if (snp_vmpl) { - struct svsm_call call = {}; - unsigned long flags; - int ret; - - local_irq_save(flags); - - /* - * SVSM_CORE_REMAP_CA call: - * RAX = 0 (Protocol=0, CallID=0) - * RCX = New CA GPA - */ - call.caa = svsm_get_caa(); - call.rax = SVSM_CORE_CALL(SVSM_CORE_REMAP_CA); - call.rcx = this_cpu_read(svsm_caa_pa); - ret = svsm_perform_call_protocol(&call); - if (ret) - panic("Can't remap the SVSM CA, ret=%d, rax_out=0x%llx\n", - ret, call.rax_out); - + if (snp_vmpl) sev_cfg.use_cas = true; - local_irq_restore(flags); - } - sev_es_setup_play_dead(); /* Secondary CPUs use the runtime #VC handler */ diff --git a/arch/x86/include/asm/sev-internal.h b/arch/x86/include/asm/sev-internal.h index 9ff824540b48..f98f080410ad 100644 --- a/arch/x86/include/asm/sev-internal.h +++ b/arch/x86/include/asm/sev-internal.h @@ -62,22 +62,6 @@ DECLARE_PER_CPU(u64, svsm_caa_pa); extern u64 boot_svsm_caa_pa; -static __always_inline struct svsm_ca *svsm_get_caa(void) -{ - if (sev_cfg.use_cas) - return this_cpu_read(svsm_caa); - else - return rip_rel_ptr(&boot_svsm_ca_page); -} - -static __always_inline u64 svsm_get_caa_pa(void) -{ - if (sev_cfg.use_cas) - return this_cpu_read(svsm_caa_pa); - else - return boot_svsm_caa_pa; -} - enum es_result verify_exception_info(struct ghcb *ghcb, struct es_em_ctxt *ctxt); void vc_forward_exception(struct es_em_ctxt *ctxt); -- 2.51.0.268.g9569e192d0-goog