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Peter Anvin" , Michael Roth , Joerg Roedel , Dionna Glaze , Andy Lutomirski , Peter Zijlstra Subject: [PATCH v7 3/6] x86/sev: Allow for use of the early boot GHCB for PSC requests Date: Tue, 4 Apr 2023 12:23:03 -0500 Message-ID: <79ae3cce825217f150560a1ab6fc1fd947b406c4.1680628986.git.thomas.lendacky@amd.com> X-Mailer: git-send-email 2.40.0 In-Reply-To: References: <20230330114956.20342-1-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.180.168.240] X-ClientProxiedBy: SATLEXMB04.amd.com (10.181.40.145) To SATLEXMB04.amd.com (10.181.40.145) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: DS1PEPF0000E641:EE_|MW5PR12MB5600:EE_ X-MS-Office365-Filtering-Correlation-Id: 849db2aa-54fa-4b9e-092e-08db353157d9 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:165.204.84.17;CTRY:US;LANG:en;SCL:1;SRV:;IPV:CAL;SFV:NSPM;H:SATLEXMB04.amd.com;PTR:InfoDomainNonexistent;CAT:NONE;SFS:(13230028)(4636009)(39860400002)(346002)(396003)(376002)(136003)(451199021)(36840700001)(46966006)(40470700004)(316002)(54906003)(26005)(2616005)(36860700001)(336012)(426003)(110136005)(478600001)(47076005)(16526019)(82740400003)(186003)(6666004)(8676002)(70206006)(83380400001)(70586007)(86362001)(4326008)(2906002)(7416002)(81166007)(41300700001)(5660300002)(8936002)(40460700003)(40480700001)(356005)(82310400005)(36756003)(36900700001);DIR:OUT;SFP:1101; X-OriginatorOrg: amd.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 04 Apr 2023 17:23:44.5943 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 849db2aa-54fa-4b9e-092e-08db353157d9 X-MS-Exchange-CrossTenant-Id: 3dd8961f-e488-4e60-8e11-a82d994e183d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=3dd8961f-e488-4e60-8e11-a82d994e183d;Ip=[165.204.84.17];Helo=[SATLEXMB04.amd.com] X-MS-Exchange-CrossTenant-AuthSource: DS1PEPF0000E641.namprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: MW5PR12MB5600 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Using a GHCB for a page stage change (as opposed to the MSR protocol) allows for multiple pages to be processed in a single request. In prep for early PSC requests in support of unaccepted memory, update the invocation of vmgexit_psc() to be able to use the early boot GHCB and not just the per-CPU GHCB structure. In order to use the proper GHCB (early boot vs per-CPU), set a flag that indicates when the per-CPU GHCBs are available and registered. For APs, the per-CPU GHCBs are created before they are started and registered upon startup, so this flag can be used globally for the BSP and APs instead of creating a per-CPU flag. This will allow for a significant reduction in the number of MSR protocol page state change requests when accepting memory. Signed-off-by: Tom Lendacky --- arch/x86/kernel/sev.c | 61 +++++++++++++++++++++++++++---------------- 1 file changed, 38 insertions(+), 23 deletions(-) diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c index a3d76eb344d6..1717bc4558f7 100644 --- a/arch/x86/kernel/sev.c +++ b/arch/x86/kernel/sev.c @@ -117,7 +117,19 @@ static DEFINE_PER_CPU(struct sev_es_save_area *, sev_v= msa); =20 struct sev_config { __u64 debug : 1, - __reserved : 63; + + /* + * A flag used by __set_pages_state() that indicates when the + * per-CPU GHCB has been created and registered and thus can be + * used by the BSP instead of the early boot GHCB. + * + * For APs, the per-CPU GHCB is created before they are started + * and registered upon startup, so this flag can be used globally + * for the BSP and APs. + */ + ghcbs_initialized : 1, + + __reserved : 62; }; =20 static struct sev_config sev_cfg __read_mostly; @@ -660,7 +672,7 @@ static void pvalidate_pages(unsigned long vaddr, unsign= ed long npages, bool vali } } =20 -static void __init early_set_pages_state(unsigned long paddr, unsigned lon= g npages, enum psc_op op) +static void early_set_pages_state(unsigned long paddr, unsigned long npage= s, enum psc_op op) { unsigned long paddr_end; u64 val; @@ -754,26 +766,13 @@ void __init snp_prep_memory(unsigned long paddr, unsi= gned int sz, enum psc_op op WARN(1, "invalid memory op %d\n", op); } =20 -static int vmgexit_psc(struct snp_psc_desc *desc) +static int vmgexit_psc(struct ghcb *ghcb, struct snp_psc_desc *desc) { int cur_entry, end_entry, ret =3D 0; struct snp_psc_desc *data; - struct ghcb_state state; struct es_em_ctxt ctxt; - unsigned long flags; - struct ghcb *ghcb; =20 - /* - * __sev_get_ghcb() needs to run with IRQs disabled because it is using - * a per-CPU GHCB. - */ - local_irq_save(flags); - - ghcb =3D __sev_get_ghcb(&state); - if (!ghcb) { - ret =3D 1; - goto out_unlock; - } + vc_ghcb_invalidate(ghcb); =20 /* Copy the input desc into GHCB shared buffer */ data =3D (struct snp_psc_desc *)ghcb->shared_buffer; @@ -830,20 +829,18 @@ static int vmgexit_psc(struct snp_psc_desc *desc) } =20 out: - __sev_put_ghcb(&state); - -out_unlock: - local_irq_restore(flags); - return ret; } =20 static void __set_pages_state(struct snp_psc_desc *data, unsigned long vad= dr, unsigned long vaddr_end, int op) { + struct ghcb_state state; struct psc_hdr *hdr; struct psc_entry *e; + unsigned long flags; unsigned long pfn; + struct ghcb *ghcb; int i; =20 hdr =3D &data->hdr; @@ -873,8 +870,20 @@ static void __set_pages_state(struct snp_psc_desc *dat= a, unsigned long vaddr, i++; } =20 - if (vmgexit_psc(data)) + local_irq_save(flags); + + if (sev_cfg.ghcbs_initialized) + ghcb =3D __sev_get_ghcb(&state); + else + ghcb =3D boot_ghcb; + + if (!ghcb || vmgexit_psc(ghcb, data)) sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_PSC); + + if (sev_cfg.ghcbs_initialized) + __sev_put_ghcb(&state); + + local_irq_restore(flags); } =20 static void set_pages_state(unsigned long vaddr, unsigned long npages, int= op) @@ -882,6 +891,10 @@ static void set_pages_state(unsigned long vaddr, unsig= ned long npages, int op) unsigned long vaddr_end, next_vaddr; struct snp_psc_desc desc; =20 + /* Use the MSR protocol when a GHCB is not available. */ + if (!boot_ghcb) + return early_set_pages_state(__pa(vaddr), npages, op); + vaddr =3D vaddr & PAGE_MASK; vaddr_end =3D vaddr + (npages << PAGE_SHIFT); =20 @@ -1259,6 +1272,8 @@ void setup_ghcb(void) if (cc_platform_has(CC_ATTR_GUEST_SEV_SNP)) snp_register_per_cpu_ghcb(); =20 + sev_cfg.ghcbs_initialized =3D true; + return; } =20 --=20 2.40.0