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Shutemov" , Andi Kleen , tony.luck@intel.com, marcorr@google.com, sathyanarayanan.kuppuswamy@linux.intel.com References: <20210820155918.7518-1-brijesh.singh@amd.com> <20210820155918.7518-7-brijesh.singh@amd.com> Message-ID: <60d6a70d-22ab-9e17-b243-7f5669b4b70d@amd.com> Date: Thu, 30 Sep 2021 09:19:52 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Content-Language: en-US X-ClientProxiedBy: BY3PR10CA0021.namprd10.prod.outlook.com (2603:10b6:a03:255::26) To SN6PR12MB2718.namprd12.prod.outlook.com (2603:10b6:805:6f::22) MIME-Version: 1.0 Received: from Brijeshs-MacBook-Pro.local (50.237.87.214) by BY3PR10CA0021.namprd10.prod.outlook.com (2603:10b6:a03:255::26) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.20.4566.16 via Frontend Transport; Thu, 30 Sep 2021 16:19:54 +0000 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 56b4d23f-46d8-4b25-f7fa-08d9842e244d X-MS-TrafficTypeDiagnostic: SA0PR12MB4557: X-MS-Exchange-Transport-Forked: True X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:519; 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I'll work to improve the commit description. > Also, set_direct_map_invalid_noflush() simply clears the Present and RW > bit of a pte. > > So what's up? The set_direct_map_invalid_noflush() does two steps 1) Split the host page table (if needed) 2) Clear the present and RW bit from pte In previous patches I was using the set_memory_4k() to split the direct map before adding the pages in the RMP table. Based on Sean's review comment [1], I switched to using set_direct_map_invalid_noflush() so that page is not just split but also removed from the direct map. The thought process is if in the future  set_direct_map_default_noflush() is improved to restore the large mapping then it will all work transparently. [1] https://lore.kernel.org/lkml/YO9kP1v0TAFXISHD@google.com/#t >> Signed-off-by: Brijesh Singh >> --- >> arch/x86/kernel/sev.c | 61 ++++++++++++++++++++++++++++++++++++++++++- >> 1 file changed, 60 insertions(+), 1 deletion(-) >> >> diff --git a/arch/x86/kernel/sev.c b/arch/x86/kernel/sev.c >> index 8627c49666c9..bad41deb8335 100644 >> --- a/arch/x86/kernel/sev.c >> +++ b/arch/x86/kernel/sev.c >> @@ -2441,10 +2441,42 @@ int psmash(u64 pfn) >> } >> EXPORT_SYMBOL_GPL(psmash); >> >> +static int restore_direct_map(u64 pfn, int npages) > restore_pages_in_direct_map() > >> +{ >> + int i, ret = 0; >> + >> + for (i = 0; i < npages; i++) { >> + ret = set_direct_map_default_noflush(pfn_to_page(pfn + i)); >> + if (ret) >> + goto cleanup; >> + } > So this is looping over a set of virtually contiguous pages, I presume, > and if so, you should add a function called > > set_memory_p_rw() > > to arch/x86/mm/pat/set_memory.c which does > > return change_page_attr_set(&addr, numpages, __pgprot(_PAGE_PRESENT | _PAGE_RW), 0); > > so that you can do all pages in one go. I will look into it. thanks