| Message ID | a0bf771e1472eb1a6a241acd2e16c98ab8ac9253.1708390906.git.ashish.kalra@amd.com |
|---|---|
| State | New |
| Headers | show |
| Series | x86/snp: Add kexec support | expand |
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 <ashish.kalra@amd.com> >> >> 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 <ashish.kalra@amd.com> >> --- >> 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
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; }