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Tue, 22 Jul 2025 00:29:56 -0700 (PDT) Date: Tue, 22 Jul 2025 09:27:16 +0200 In-Reply-To: <20250722072708.2079165-24-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: <20250722072708.2079165-24-ardb+git@google.com> X-Developer-Key: i=ardb@kernel.org; a=openpgp; fpr=F43D03328115A198C90016883D200E9CA6329909 X-Developer-Signature: v=1; a=openpgp-sha256; l=5890; i=ardb@kernel.org; h=from:subject; bh=Xu3nJVJSBr+OOcY1i2lptxUFYocnqV8hTyJhBKvJwXs=; b=owGbwMvMwCVmkMcZplerG8N4Wi2JIaPetjA88pCy2hqGazLZv19LJifOt1JIfcj+esHStjJd/ ZuXN07tKGVhEONikBVTZBGY/ffdztMTpWqdZ8nCzGFlAhnCwMUpABOZvIyR4UTHPKWmLSJfj9+K XDQ79jPL/hdrp815ZS+Y/eNM9PxIBmFGhubz+ZdWLXRvvMI+K0z7/H7BCPsbQvcfTWT3NKu9rto cyw0A X-Mailer: git-send-email 2.50.0.727.gbf7dc18ff4-goog Message-ID: <20250722072708.2079165-31-ardb+git@google.com> Subject: [PATCH v6 07/22] 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 , Kevin Loughlin , Tom Lendacky , Josh Poimboeuf , Peter Zijlstra , Nikunj A Dadhania 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 | 40 ++------------------ arch/x86/boot/startup/sev-shared.c | 35 +++++++++++++++++ arch/x86/boot/startup/sev-startup.c | 29 +------------- 3 files changed, 39 insertions(+), 65 deletions(-) diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c index 6c0f91d38595..f714235d3222 100644 --- a/arch/x86/boot/compressed/sev.c +++ b/arch/x86/boot/compressed/sev.c @@ -60,46 +60,12 @@ 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); - - /* Save the current GHCB MSR value */ - msr =3D sev_es_rd_ghcb_msr(); - - /* 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); - - /* Restore the GHCB MSR value */ - sev_es_wr_ghcb_msr(msr); - - /* - * 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) { if (!sev_snp_enabled()) return; =20 - __page_state_change(paddr, SNP_PAGE_STATE_PRIVATE); + __page_state_change(paddr, paddr, SNP_PAGE_STATE_PRIVATE); } =20 void snp_set_page_shared(unsigned long paddr) @@ -107,7 +73,7 @@ void snp_set_page_shared(unsigned long paddr) if (!sev_snp_enabled()) return; =20 - __page_state_change(paddr, SNP_PAGE_STATE_SHARED); + __page_state_change(paddr, paddr, SNP_PAGE_STATE_SHARED); } =20 bool early_setup_ghcb(void) @@ -133,7 +99,7 @@ bool early_setup_ghcb(void) void snp_accept_memory(phys_addr_t start, phys_addr_t end) { 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); } =20 void sev_es_shutdown_ghcb(void) diff --git a/arch/x86/boot/startup/sev-shared.c b/arch/x86/boot/startup/sev= -shared.c index 852c8443ed1a..1da1afa8677a 100644 --- a/arch/x86/boot/startup/sev-shared.c +++ b/arch/x86/boot/startup/sev-shared.c @@ -653,6 +653,41 @@ 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, 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(vaddr, paddr, false); + + /* Save the current GHCB MSR value */ + msr =3D sev_es_rd_ghcb_msr(); + + /* 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); + + /* Restore the GHCB MSR value */ + sev_es_wr_ghcb_msr(msr); + + /* + * 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 8a06f6026101..5eb7d939ebd3 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