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Wed, 09 Jul 2025 01:11:16 -0700 (PDT) Date: Wed, 9 Jul 2025 10:08:48 +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=2568; i=ardb@kernel.org; h=from:subject; bh=MfTuguQkKRk7zPgVN6OJ7MlTRDEEvX8Q+P+1ZFmIP8Y=; b=owGbwMvMwCVmkMcZplerG8N4Wi2JISNPef3SyAvfkifl+T25/461Z4quEPvZ9/VBZ2M/2/cfr orKdm3uKGVhEONikBVTZBGY/ffdztMTpWqdZ8nCzGFlAhnCwMUpABN5UMTI0FN28a9cwYFTjqFP s4Rur/dQD896kae+pvceb8LPM19V/jH8rwiVkHpz/O6NA5pXnpndspzBUX2pc4tya15k8YHV6ou 38AAA X-Mailer: git-send-email 2.50.0.727.gbf7dc18ff4-goog Message-ID: <20250709080840.2233208-33-ardb+git@google.com> Subject: [PATCH v4 07/24] x86/sev: Move MSR save/restore out of early page state change helper 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 The function __page_state_change() in the decompressor is very similar to the loop in early_set_pages_state(), and they can share this code once the MSR save/restore is moved out. This also avoids doing the preserve/restore for each page in a longer sequence unnecessarily. This simplifies subsequent changes, where the APIs used by __page_state_change() are modified for better separation between startup code and ordinary code. Signed-off-by: Ard Biesheuvel --- arch/x86/boot/compressed/sev.c | 17 +++++++++++------ 1 file changed, 11 insertions(+), 6 deletions(-) diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c index 6c0f91d38595..f00f68175f14 100644 --- a/arch/x86/boot/compressed/sev.c +++ b/arch/x86/boot/compressed/sev.c @@ -71,9 +71,6 @@ static void __page_state_change(unsigned long paddr, enum= psc_op op) if (op =3D=3D SNP_PAGE_STATE_SHARED) pvalidate_4k_page(paddr, paddr, false); =20 - /* 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(); @@ -83,9 +80,6 @@ static void __page_state_change(unsigned long paddr, enum= psc_op op) 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); =20 - /* 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. @@ -96,18 +90,26 @@ static void __page_state_change(unsigned long paddr, en= um psc_op op) =20 void snp_set_page_private(unsigned long paddr) { + u64 msr; + if (!sev_snp_enabled()) return; =20 + msr =3D sev_es_rd_ghcb_msr(); __page_state_change(paddr, SNP_PAGE_STATE_PRIVATE); + sev_es_wr_ghcb_msr(msr); } =20 void snp_set_page_shared(unsigned long paddr) { + u64 msr; + if (!sev_snp_enabled()) return; =20 + msr =3D sev_es_rd_ghcb_msr(); __page_state_change(paddr, SNP_PAGE_STATE_SHARED); + sev_es_wr_ghcb_msr(msr); } =20 bool early_setup_ghcb(void) @@ -132,8 +134,11 @@ bool early_setup_ghcb(void) =20 void snp_accept_memory(phys_addr_t start, phys_addr_t end) { + u64 msr =3D sev_es_rd_ghcb_msr(); + for (phys_addr_t pa =3D start; pa < end; pa +=3D PAGE_SIZE) __page_state_change(pa, SNP_PAGE_STATE_PRIVATE); + sev_es_wr_ghcb_msr(msr); } =20 void sev_es_shutdown_ghcb(void) --=20 2.50.0.727.gbf7dc18ff4-goog