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David Alan Gilbert" , tony.luck@intel.com, marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com Subject: Re: [PATCH v8 15/40] x86/mm: Add support to validate memory when changing C-bit Message-ID: References: <20211210154332.11526-1-brijesh.singh@amd.com> <20211210154332.11526-16-brijesh.singh@amd.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211210154332.11526-16-brijesh.singh@amd.com> X-ClientProxiedBy: SJ0PR05CA0200.namprd05.prod.outlook.com (2603:10b6:a03:330::25) To SN6PR10MB2576.namprd10.prod.outlook.com (2603:10b6:805:44::15) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 88f8f182-298d-4f58-2f5f-08d9cfd2017b X-MS-TrafficTypeDiagnostic: SN6PR10MB2573:EE_ X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:8273; 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:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:SN6PR10MB2576.namprd10.prod.outlook.com;PTR:;CAT:NONE;SFS:(7916004)(366004)(26005)(86362001)(2906002)(186003)(66556008)(7406005)(7416002)(4326008)(38100700002)(6506007)(5660300002)(8936002)(6916009)(54906003)(9686003)(6666004)(4001150100001)(53546011)(44832011)(6486002)(15650500001)(6512007)(316002)(33716001)(83380400001)(66476007)(508600001)(8676002)(66946007);DIR:OUT;SFP:1101; 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Issue the page state change VMGEXIT to add the memory region in > the RMP table. > 2. Validate the memory region after the RMP entry is added. > > To maintain the security guarantees, if the page is transitioned from > private to shared, then perform the following before encryption attribute > is removed from the page table: > > 1. Invalidate the page. > 2. Issue the page state change VMGEXIT to remove the page from RMP table. > > To change the page state in the RMP table, use the Page State Change > VMGEXIT defined in the GHCB specification. > > The GHCB specification provides the flexibility to use either 4K or 2MB > page size in during the page state change (PSC) request. For now use the > 4K page size for all the PSC until page size tracking is supported in the > kernel. > > Signed-off-by: Brijesh Singh [snip] > diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c > index 2971aa280ce6..35c772bf9f6c 100644 > --- a/arch/x86/kernel/sev.c > +++ b/arch/x86/kernel/sev.c > @@ -574,7 +574,7 @@ static void pvalidate_pages(unsigned long vaddr, unsigned int npages, bool valid > } > } > > -static void __init early_set_page_state(unsigned long paddr, unsigned int npages, enum psc_op op) > +static void __init early_set_pages_state(unsigned long paddr, unsigned int npages, enum psc_op op) Is there a need to change the name? "npages" can take a value of 1 too. Hence, early_set_page_state() appears to be a better name! > + /* > + * Page State Change VMGEXIT can pass error code through > + * exit_info_2. > + */ Collapse into one line? > +void snp_set_memory_shared(unsigned long vaddr, unsigned int npages) > +{ > + if (!cc_platform_has(CC_ATTR_SEV_SNP)) > + return; > + > + pvalidate_pages(vaddr, npages, 0); Replace '0' with "false"? > + > + set_pages_state(vaddr, npages, SNP_PAGE_STATE_SHARED); > +} > + > +void snp_set_memory_private(unsigned long vaddr, unsigned int npages) > +{ > + if (!cc_platform_has(CC_ATTR_SEV_SNP)) > + return; > + > + set_pages_state(vaddr, npages, SNP_PAGE_STATE_PRIVATE); > + > + pvalidate_pages(vaddr, npages, 1); Replace '1' with "true"? Venu