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Wed, 09 Jul 2025 01:11:18 -0700 (PDT) Date: Wed, 9 Jul 2025 10:08:49 +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=5666; i=ardb@kernel.org; h=from:subject; bh=pprdQAqCpx32HnISI4w8qM66RBXLsKFTiE22x4mWR5w=; b=owGbwMvMwCVmkMcZplerG8N4Wi2JISNPecuP0nfZXy1czMRrwuw2Oluv/PdG7ZRTjbvrFjHP7 OowtrqOUhYGMS4GWTFFFoHZf9/tPD1RqtZ5lizMHFYmkCEMXJwCMBFBFoa/YvVZKy4Hl+1L2m92 2+h4d4ByhOA/N71dYbvjpa6LRweWMPxk/Pz/WODL9iP3GNZatJ1f8mty1c3LT2+wcHOsYJHaGHm PAwA= X-Mailer: git-send-email 2.50.0.727.gbf7dc18ff4-goog Message-ID: <20250709080840.2233208-34-ardb+git@google.com> Subject: [PATCH v4 08/24] x86/sev: Share implementation of MSR-based page state change 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 Both the decompressor and the SEV startup code implement the exact same sequence for invoking the MSR based communication protocol to effectuate a page state change. Before tweaking the internal APIs used in both versions, merge them and share them so those tweaks are only needed in a single place. Signed-off-by: Ard Biesheuvel --- arch/x86/boot/compressed/sev.c | 34 ++------------------ arch/x86/boot/startup/sev-shared.c | 29 +++++++++++++++++ arch/x86/boot/startup/sev-startup.c | 29 +---------------- 3 files changed, 33 insertions(+), 59 deletions(-) diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c index f00f68175f14..6d3ed7ed03a4 100644 --- a/arch/x86/boot/compressed/sev.c +++ b/arch/x86/boot/compressed/sev.c @@ -60,34 +60,6 @@ static bool sev_snp_enabled(void) return sev_status & MSR_AMD64_SEV_SNP_ENABLED; } =20 -static void __page_state_change(unsigned long paddr, enum psc_op op) -{ - u64 val, msr; - - /* - * If private -> shared then invalidate the page before requesting the - * state change in the RMP table. - */ - if (op =3D=3D SNP_PAGE_STATE_SHARED) - pvalidate_4k_page(paddr, paddr, false); - - /* Issue VMGEXIT to change the page state in RMP table. */ - sev_es_wr_ghcb_msr(GHCB_MSR_PSC_REQ_GFN(paddr >> PAGE_SHIFT, op)); - VMGEXIT(); - - /* Read the response of the VMGEXIT. */ - val =3D sev_es_rd_ghcb_msr(); - if ((GHCB_RESP_CODE(val) !=3D GHCB_MSR_PSC_RESP) || GHCB_MSR_PSC_RESP_VAL= (val)) - sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PSC); - - /* - * Now that page state is changed in the RMP table, validate it so that i= t is - * consistent with the RMP entry. - */ - if (op =3D=3D SNP_PAGE_STATE_PRIVATE) - pvalidate_4k_page(paddr, paddr, true); -} - void snp_set_page_private(unsigned long paddr) { u64 msr; @@ -96,7 +68,7 @@ void snp_set_page_private(unsigned long paddr) return; =20 msr =3D sev_es_rd_ghcb_msr(); - __page_state_change(paddr, SNP_PAGE_STATE_PRIVATE); + __page_state_change(paddr, paddr, SNP_PAGE_STATE_PRIVATE); sev_es_wr_ghcb_msr(msr); } =20 @@ -108,7 +80,7 @@ void snp_set_page_shared(unsigned long paddr) return; =20 msr =3D sev_es_rd_ghcb_msr(); - __page_state_change(paddr, SNP_PAGE_STATE_SHARED); + __page_state_change(paddr, paddr, SNP_PAGE_STATE_SHARED); sev_es_wr_ghcb_msr(msr); } =20 @@ -137,7 +109,7 @@ void snp_accept_memory(phys_addr_t start, phys_addr_t e= nd) u64 msr =3D sev_es_rd_ghcb_msr(); =20 for (phys_addr_t pa =3D start; pa < end; pa +=3D PAGE_SIZE) - __page_state_change(pa, SNP_PAGE_STATE_PRIVATE); + __page_state_change(pa, pa, SNP_PAGE_STATE_PRIVATE); sev_es_wr_ghcb_msr(msr); } =20 diff --git a/arch/x86/boot/startup/sev-shared.c b/arch/x86/boot/startup/sev= -shared.c index 7ca59038269f..f553268d31d7 100644 --- a/arch/x86/boot/startup/sev-shared.c +++ b/arch/x86/boot/startup/sev-shared.c @@ -640,6 +640,35 @@ static void __head pvalidate_4k_page(unsigned long vad= dr, unsigned long paddr, } } =20 +static void __head __page_state_change(unsigned long vaddr, unsigned long = paddr, + enum psc_op op) +{ + u64 val; + + /* + * If private -> shared then invalidate the page before requesting the + * state change in the RMP table. + */ + if (op =3D=3D SNP_PAGE_STATE_SHARED) + pvalidate_4k_page(vaddr, paddr, false); + + /* Issue VMGEXIT to change the page state in RMP table. */ + sev_es_wr_ghcb_msr(GHCB_MSR_PSC_REQ_GFN(paddr >> PAGE_SHIFT, op)); + VMGEXIT(); + + /* Read the response of the VMGEXIT. */ + val =3D sev_es_rd_ghcb_msr(); + if ((GHCB_RESP_CODE(val) !=3D GHCB_MSR_PSC_RESP) || GHCB_MSR_PSC_RESP_VAL= (val)) + sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PSC); + + /* + * Now that page state is changed in the RMP table, validate it so that i= t is + * consistent with the RMP entry. + */ + if (op =3D=3D SNP_PAGE_STATE_PRIVATE) + pvalidate_4k_page(vaddr, paddr, true); +} + /* * Maintain the GPA of the SVSM Calling Area (CA) in order to utilize the = SVSM * services needed when not running in VMPL0. diff --git a/arch/x86/boot/startup/sev-startup.c b/arch/x86/boot/startup/se= v-startup.c index 8edf1ba78a48..2ffd8bf09357 100644 --- a/arch/x86/boot/startup/sev-startup.c +++ b/arch/x86/boot/startup/sev-startup.c @@ -135,7 +135,6 @@ early_set_pages_state(unsigned long vaddr, unsigned lon= g paddr, unsigned long npages, enum psc_op op) { unsigned long paddr_end; - u64 val; =20 vaddr =3D vaddr & PAGE_MASK; =20 @@ -143,37 +142,11 @@ early_set_pages_state(unsigned long vaddr, unsigned l= ong paddr, paddr_end =3D paddr + (npages << PAGE_SHIFT); =20 while (paddr < paddr_end) { - /* Page validation must be rescinded before changing to shared */ - if (op =3D=3D SNP_PAGE_STATE_SHARED) - pvalidate_4k_page(vaddr, paddr, false); - - /* - * Use the MSR protocol because this function can be called before - * the GHCB is established. - */ - sev_es_wr_ghcb_msr(GHCB_MSR_PSC_REQ_GFN(paddr >> PAGE_SHIFT, op)); - VMGEXIT(); - - val =3D sev_es_rd_ghcb_msr(); - - if (GHCB_RESP_CODE(val) !=3D GHCB_MSR_PSC_RESP) - goto e_term; - - if (GHCB_MSR_PSC_RESP_VAL(val)) - goto e_term; - - /* Page validation must be performed after changing to private */ - if (op =3D=3D SNP_PAGE_STATE_PRIVATE) - pvalidate_4k_page(vaddr, paddr, true); + __page_state_change(vaddr, paddr, op); =20 vaddr +=3D PAGE_SIZE; paddr +=3D PAGE_SIZE; } - - return; - -e_term: - sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PSC); } =20 void __head early_snp_set_memory_private(unsigned long vaddr, unsigned lon= g paddr, --=20 2.50.0.727.gbf7dc18ff4-goog