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Berrange" , Eduardo Habkost , Eric Blake , Markus Armbruster , Marcelo Tosatti , Zhao Liu , Nikunj A Dadhania , Tom Lendacky , Michael Roth , Neeraj Upadhyay , Roy Hopkins Subject: [RFC PATCH 3/7] target/i386: SEV: Add support for enabling debug-swap SEV feature Date: Thu, 11 Sep 2025 17:24:22 +0530 Message-ID: <0a77cf472bc36fee7c1be78fc7d6d514d22bca9a.1757589490.git.naveen@kernel.org> X-Mailer: git-send-email 2.50.1 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=172.234.252.31; envelope-from=naveen@kernel.org; helo=sea.source.kernel.org X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @kernel.org) X-ZM-MESSAGEID: 1757592045459116600 Content-Type: text/plain; charset="utf-8" Add support for enabling debug-swap VMSA SEV feature in SEV-ES and SEV-SNP guests through a new "debug-swap" boolean property on SEV guest objects. Though the boolean property is available for plain SEV guests, check_sev_features() will reject setting this for plain SEV guests. Add helpers for setting and querying the VMSA SEV features so that they can be re-used for subsequent VMSA SEV features, and convert the existing SVM_SEV_FEAT_SNP_ACTIVE definition to use the BIT() macro for consistency with the new feature flag. Sample command-line: -machine q35,confidential-guest-support=3Dsev0 \ -object sev-snp-guest,id=3Dsev0,cbitpos=3D51,reduced-phys-bits=3D1,debug-= swap=3Don Signed-off-by: Naveen N Rao (AMD) --- target/i386/sev.h | 3 ++- target/i386/sev.c | 29 +++++++++++++++++++++++++++++ qapi/qom.json | 6 +++++- 3 files changed, 36 insertions(+), 2 deletions(-) diff --git a/target/i386/sev.h b/target/i386/sev.h index 9db1a802f6bb..8e09b2ce1976 100644 --- a/target/i386/sev.h +++ b/target/i386/sev.h @@ -44,7 +44,8 @@ bool sev_snp_enabled(void); #define SEV_SNP_POLICY_SMT 0x10000 #define SEV_SNP_POLICY_DBG 0x80000 =20 -#define SVM_SEV_FEAT_SNP_ACTIVE 1 +#define SVM_SEV_FEAT_SNP_ACTIVE BIT(0) +#define SVM_SEV_FEAT_DEBUG_SWAP BIT(5) =20 typedef struct SevKernelLoaderContext { char *setup_data; diff --git a/target/i386/sev.c b/target/i386/sev.c index fa23b5c38e9b..b3e4d0f2c1d5 100644 --- a/target/i386/sev.c +++ b/target/i386/sev.c @@ -319,6 +319,20 @@ sev_set_guest_state(SevCommonState *sev_common, SevSta= te new_state) sev_common->state =3D new_state; } =20 +static bool is_sev_feature_set(SevCommonState *sev_common, uint64_t featur= e) +{ + return !!(sev_common->sev_features & feature); +} + +static void sev_set_feature(SevCommonState *sev_common, uint64_t feature, = bool value) +{ + if (value) { + sev_common->sev_features |=3D feature; + } else { + sev_common->sev_features &=3D ~feature; + } +} + static void sev_ram_block_added(RAMBlockNotifier *n, void *host, size_t size, size_t max_size) @@ -2732,6 +2746,16 @@ static int cgs_set_guest_policy(ConfidentialGuestPol= icyType policy_type, return 0; } =20 +static bool sev_common_get_debug_swap(Object *obj, Error **errp) +{ + return is_sev_feature_set(SEV_COMMON(obj), SVM_SEV_FEAT_DEBUG_SWAP); +} + +static void sev_common_set_debug_swap(Object *obj, bool value, Error **err= p) +{ + sev_set_feature(SEV_COMMON(obj), SVM_SEV_FEAT_DEBUG_SWAP, value); +} + static void sev_common_class_init(ObjectClass *oc, const void *data) { @@ -2749,6 +2773,11 @@ sev_common_class_init(ObjectClass *oc, const void *d= ata) sev_common_set_kernel_hashes); object_class_property_set_description(oc, "kernel-hashes", "add kernel hashes to guest firmware for measured Linux boot"); + object_class_property_add_bool(oc, "debug-swap", + sev_common_get_debug_swap, + sev_common_set_debug_swap); + object_class_property_set_description(oc, "debug-swap", + "enable virtualization of debug registers"); } =20 static void diff --git a/qapi/qom.json b/qapi/qom.json index 830cb2ffe781..71cd8ad588b5 100644 --- a/qapi/qom.json +++ b/qapi/qom.json @@ -1010,13 +1010,17 @@ # designated guest firmware page for measured boot with -kernel # (default: false) (since 6.2) # +# @debug-swap: enable virtualization of debug registers (default: false) +# (since 10.2) +# # Since: 9.1 ## { 'struct': 'SevCommonProperties', 'data': { '*sev-device': 'str', '*cbitpos': 'uint32', 'reduced-phys-bits': 'uint32', - '*kernel-hashes': 'bool' } } + '*kernel-hashes': 'bool', + '*debug-swap': 'bool' } } =20 ## # @SevGuestProperties: --=20 2.50.1