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David Alan Gilbert" , tony.luck@intel.com, marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com Subject: Re: [PATCH v8 12/40] x86/sev: Add helper for validating pages in early enc attribute changes Message-ID: References: <20211210154332.11526-1-brijesh.singh@amd.com> <20211210154332.11526-13-brijesh.singh@amd.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211210154332.11526-13-brijesh.singh@amd.com> X-ClientProxiedBy: BY5PR17CA0033.namprd17.prod.outlook.com (2603:10b6:a03:1b8::46) 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: 5b77e7dd-9038-4af9-c871-08d9cf10c167 X-MS-TrafficTypeDiagnostic: SN6PR10MB3022:EE_ X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:5797; X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: wX7eYj/Ts1gBnoDUxyBSeup5lONK2YDjPsFGTEWsJrpJrDd2wTg+Ku7NWcXwfwmU61kGHF9Bd24o5dzxzgJd6x9kwexl2/ipP43PJz0GKK0KVKrmM4/jGD0UXqNqkLtnD4uKOD56s+TXfaqbc6SRjuldGuiU+SEk2R8Z1UFIATQZR2FFF40ceXojaQmCxF6HMsr1dlcHmcn0C0RVTLOu3+p5DFqEiY5KlCQNcK3VRlogYud7sa1SKN0yVfYfSpHrdDYm3E5tmFohtbCRFXHiOW7KALSkiPhE3Q+K93PnGmtrA25c/eQwgq4Br/6uv9vR2Pa7+VlMytwiSiGHHS0+itd+vIP2oIDEAGRSdY4fxDqkOvSD5LvPw2gn+AYHaJl9v19aV7u9R+FhAW8lH8j3BD2cFw3Vntp0ppEZsPnf/QEvAUqPl6ZQ7OHrl7PXiEqojUVp6e9rXfk4lnFD7tXKa3IZt+1hi6v1/+j6H339qoxdyn2X6zF/ErdKWQPye9WYMCyjdBNjxZtM0O/84uwA89bXimd9KDbOipNFzCX5PiROpzGrw3hu9Jc+eXoSnAPApRMdfgCHJHPcd7M51KiN7czuRmHx+o44PPkBAQNQ0879MJ9sNq1OjqbXS+CFI0iJZIMfxfC6qy9eW1oS1OdDcQ== 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)(6486002)(316002)(7406005)(44832011)(186003)(7416002)(4326008)(66476007)(6512007)(38100700002)(508600001)(33716001)(66556008)(9686003)(4001150100001)(54906003)(66946007)(86362001)(8936002)(53546011)(8676002)(2906002)(6916009)(6666004)(26005)(6506007)(5660300002)(83380400001);DIR:OUT;SFP:1101; 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Issue the page state change VMGEXIT to add the page as a private > in the RMP table. > 2. Validate the page after its successfully added in the RMP table. > > To maintain the security guarantees, if the page is transitioned from > private to shared, then perform the following before clearing the > encryption attribute from the page table. > > 1. Invalidate the page. > 2. Issue the page state change VMGEXIT to make the page shared in the > RMP table. > > The early_set_memory_{encrypt,decrypt} can be called before the GHCB s/encrypt,decrypt/encrypted,decrypted/ > is setup, use the SNP page state MSR protocol VMGEXIT defined in the GHCB > specification to request the page state change in the RMP table. > > While at it, add a helper snp_prep_memory() that can be used outside > the sev specific files to change the page state for a specified memory > range. > > Signed-off-by: Brijesh Singh And with a few other nits below: Reviewed-by: Venu Busireddy > diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c > + > + /* > + * Ask the hypervisor to mark the memory pages as private in the RMP > + * table. > + */ Indentation is off. While at it, you may want to collapse it into a one line comment. > + early_set_page_state(paddr, npages, SNP_PAGE_STATE_PRIVATE); > + > + /* Validate the memory pages after they've been added in the RMP table. */ > + pvalidate_pages(vaddr, npages, 1); > +} > + > +void __init early_snp_set_memory_shared(unsigned long vaddr, unsigned long paddr, > + unsigned int npages) > +{ > + if (!cc_platform_has(CC_ATTR_SEV_SNP)) > + return; > + > + /* > + * Invalidate the memory pages before they are marked shared in the > + * RMP table. > + */ Collapse into one line? > + pvalidate_pages(vaddr, npages, 0); > + > + /* Ask hypervisor to mark the memory pages shared in the RMP table. */ Indentation is off. > + /* > + * ON SNP, the page state in the RMP table must happen > + * before the page table updates. > + */ > + early_snp_set_memory_shared((unsigned long)__va(pa), pa, 1); I know "1" implies "true", but to emphasize that the argument is actually a boolean, could you please change the "1" to "true?" > + } > + > /* Change the page encryption mask. */ > new_pte = pfn_pte(pfn, new_prot); > set_pte_atomic(kpte, new_pte); > + > + /* > + * If page is set encrypted in the page table, then update the RMP table to > + * add this page as private. > + */ > + if (enc) > + early_snp_set_memory_private((unsigned long)__va(pa), pa, 1); Here too, could you please change the "1" to "true?" Venu