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Content-Language: en-US To: "Kirill A. Shutemov" Cc: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, luto@kernel.org, x86@kernel.org, ardb@kernel.org, hpa@zytor.com, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, rafael@kernel.org, peterz@infradead.org, adrian.hunter@intel.com, sathyanarayanan.kuppuswamy@linux.intel.com, elena.reshetova@intel.com, jun.nakajima@intel.com, rick.p.edgecombe@intel.com, thomas.lendacky@amd.com, seanjc@google.com, kai.huang@intel.com, bhe@redhat.com, kexec@lists.infradead.org, linux-coco@lists.linux.dev, anisinha@redhat.com, michael.roth@amd.com, bdas@redhat.com, vkuznets@redhat.com, dionnaglaze@google.com, jroedel@suse.de, ashwin.kamat@broadcom.com References: <20240212104448.2589568-1-kirill.shutemov@linux.intel.com> From: "Kalra, Ashish" In-Reply-To: X-ClientProxiedBy: DM6PR21CA0006.namprd21.prod.outlook.com (2603:10b6:5:174::16) To SN6PR12MB2767.namprd12.prod.outlook.com (2603:10b6:805:75::23) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SN6PR12MB2767:EE_|SA0PR12MB4429:EE_ X-MS-Office365-Filtering-Correlation-Id: 3c540ca8-ff72-4c8d-64cd-08dc32477dfb X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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charset="us-ascii"; Format="flowed" Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org Hi Kirill, On 2/20/2024 6:42 AM, Kirill A. Shutemov wrote: > On Tue, Feb 20, 2024 at 01:18:29AM +0000, Ashish Kalra wrote: >> From: Ashish Kalra >> >> During crashkernel boot only pre-allocated crash memory is presented as >> E820_TYPE_RAM. This can cause PMD entry mapping unaccepted memory table >> to be zapped during phys_pmd_init() as SNP/TDX guest use E820_TYPE_ACPI >> to store the unaccepted memory table and pass it between the kernels on >> kexec/kdump. >> >> E820_TYPE_ACPI covers not only ACPI data, but also EFI tables and might >> be required by kernel to function properly. >> >> The problem was discovered during debugging kdump for SNP guest. The >> unaccepted memory table stored with E820_TYPE_ACPI and passed between >> the kernels on kdump was getting zapped as the PMD entry mapping this >> is above the E820_TYPE_RAM range for the reserved crashkernel memory. >> >> Signed-off-by: Ashish Kalra >> --- >> arch/x86/mm/init_64.c | 4 +++- >> 1 file changed, 3 insertions(+), 1 deletion(-) >> >> diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c >> index a0dffaca6d2b..207c6dddde0c 100644 >> --- a/arch/x86/mm/init_64.c >> +++ b/arch/x86/mm/init_64.c >> @@ -524,7 +524,9 @@ phys_pmd_init(pmd_t *pmd_page, unsigned long paddr, unsigned long paddr_end, >> !e820__mapped_any(paddr & PMD_MASK, paddr_next, >> E820_TYPE_RAM) && >> !e820__mapped_any(paddr & PMD_MASK, paddr_next, >> - E820_TYPE_RESERVED_KERN)) >> + E820_TYPE_RESERVED_KERN) && >> + !e820__mapped_any(paddr & PMD_MASK, paddr_next, >> + E820_TYPE_ACPI)) >> set_pmd_init(pmd, __pmd(0), init); >> continue; > Why do you single out phys_pmd_init()? I think it has to be addressed for > all page table levels as we do for E820_TYPE_RAM and E820_TYPE_RESERVED_KERN. I believe i only discovered the issue with PMDe's (phys_pmd_init()) because of the crashkernel reserved memory size and the E820_TYPE_ACPI physical memory range mapping on my test system, but you are right this fix needs to be done for all page table levels and i will add also the fix in phys_pte_init(), phys_pud_init() and phys_p4d_init(). Thanks, Ashish _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec