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Wed, 09 Jul 2025 01:11:22 -0700 (PDT) Date: Wed, 9 Jul 2025 10:08:51 +0200 In-Reply-To: <20250709080840.2233208-26-ardb+git@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250709080840.2233208-26-ardb+git@google.com> X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-Developer-Signature: v=1; a=openpgp-sha256; l=5481; i=ardb@kernel.org; h=from:subject; bh=sqtiD2Pgws6Z85gNpALOI39gz8WJANhOWEDVEVl7+KQ=; b=owGbwMvMwCVmkMcZplerG8N4Wi2JISNPed+G8u72JbMjBaYkqR/2cmLhtdnAJ17mWfDknZrd6 0V63w52lLIwiHExyIopsgjM/vtu5+mJUrXOs2Rh5rAygQxh4OIUgImsymZk+Ds1ahuLyJwZSjV6 ovcaXUI3nApInVf3+1nmdQ9N+Y/axYwME/tq+bbnrHzgfZbp9cYyialfw+LfnX+2IZiZp/Ofz8p qLgA= X-Mailer: git-send-email 2.50.0.727.gbf7dc18ff4-goog Message-ID: <20250709080840.2233208-36-ardb+git@google.com> Subject: [PATCH v4 10/24] 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 , Dionna Amalie Glaze , Kevin Loughlin , Tom Lendacky , Josh Poimboeuf , Peter Zijlstra Content-Transfer-Encoding: quoted-printable 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 | 7 +-- arch/x86/coco/sev/core.c | 47 +++++++++----------- arch/x86/include/asm/sev-internal.h | 16 ------- 4 files changed, 24 insertions(+), 59 deletions(-) diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c index bc23b3dabf1b..e67413bc78fd 100644 --- a/arch/x86/boot/compressed/sev.c +++ b/arch/x86/boot/compressed/sev.c @@ -37,19 +37,6 @@ struct ghcb *boot_ghcb; =20 #define __BOOT_COMPRESSED =20 -extern u64 boot_svsm_caa_pa; - -struct svsm_ca *svsm_get_caa(void) -{ - /* The decompressor is mapped 1:1 so VA =3D=3D PA */ - return (struct svsm_ca *)boot_svsm_caa_pa; -} - -u64 svsm_get_caa_pa(void) -{ - return boot_svsm_caa_pa; -} - u8 snp_vmpl; =20 /* Include code for early handlers */ diff --git a/arch/x86/boot/startup/sev-startup.c b/arch/x86/boot/startup/se= v-startup.c index e253783f6aa5..cba4fb4cace0 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); =20 -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. @@ -167,7 +164,7 @@ void __head early_snp_set_memory_private(unsigned long = vaddr, unsigned long padd * table. */ early_set_pages_state(vaddr, paddr, npages, SNP_PAGE_STATE_PRIVATE, - svsm_get_caa(), svsm_get_caa_pa()); + rip_rel_ptr(&boot_svsm_ca_page), boot_svsm_caa_pa); } =20 void __head early_snp_set_memory_shared(unsigned long vaddr, unsigned long= paddr, @@ -184,7 +181,7 @@ void __head early_snp_set_memory_shared(unsigned long v= addr, unsigned long paddr =20 /* Ask hypervisor to mark the memory pages shared in the RMP table. */ early_set_pages_state(vaddr, paddr, npages, SNP_PAGE_STATE_SHARED, - svsm_get_caa(), svsm_get_caa_pa()); + rip_rel_ptr(&boot_svsm_ca_page), boot_svsm_caa_pa); } =20 /* diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c index 7a86a2fe494d..4fe0928bc0ad 100644 --- a/arch/x86/coco/sev/core.c +++ b/arch/x86/coco/sev/core.c @@ -46,6 +46,25 @@ #include #include =20 +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 Initializa= tion State" */ #define AP_INIT_CS_LIMIT 0xffff #define AP_INIT_DS_LIMIT 0xffff @@ -1287,7 +1306,8 @@ static void __init alloc_runtime_data(int cpu) struct svsm_ca *caa; =20 /* Allocate the SVSM CA page if an SVSM is present */ - caa =3D memblock_alloc_or_panic(sizeof(*caa), PAGE_SIZE); + caa =3D cpu ? memblock_alloc_or_panic(sizeof(*caa), PAGE_SIZE) + : &boot_svsm_ca_page; =20 per_cpu(svsm_caa, cpu) =3D caa; per_cpu(svsm_caa_pa, cpu) =3D __pa(caa); @@ -1341,32 +1361,9 @@ void __init sev_es_init_vc_handling(void) init_ghcb(cpu); } =20 - /* If running under an SVSM, switch to the per-cpu CA */ - if (snp_vmpl) { - struct svsm_call call =3D {}; - unsigned long flags; - int ret; - - local_irq_save(flags); - - /* - * SVSM_CORE_REMAP_CA call: - * RAX =3D 0 (Protocol=3D0, CallID=3D0) - * RCX =3D New CA GPA - */ - call.caa =3D svsm_get_caa(); - call.rax =3D SVSM_CORE_CALL(SVSM_CORE_REMAP_CA); - call.rcx =3D this_cpu_read(svsm_caa_pa); - ret =3D svsm_perform_call_protocol(&call); - if (ret) - panic("Can't remap the SVSM CA, ret=3D%d, rax_out=3D0x%llx\n", - ret, call.rax_out); - + if (snp_vmpl) sev_cfg.use_cas =3D true; =20 - local_irq_restore(flags); - } - sev_es_setup_play_dead(); =20 /* 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 3b72d8217827..bdfe008120f3 100644 --- a/arch/x86/include/asm/sev-internal.h +++ b/arch/x86/include/asm/sev-internal.h @@ -63,22 +63,6 @@ DECLARE_PER_CPU(u64, svsm_caa_pa); =20 extern u64 boot_svsm_caa_pa; =20 -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); =20 --=20 2.50.0.727.gbf7dc18ff4-goog