Share pages before the page allocator is available, after both their direct-map and kernel-image mappings have been made shared. Preserve initial contents in a private scratch page, matching the AMD early helper, and use the existing MapGPA path and shared-page accounting.
UP per-CPU data has an image alias. Drop shared image mappings before kexec converts their backing pages to private through the direct map. Suggested-by: Kiryl Shutsemau <[email protected]> Link: https://lore.kernel.org/r/aqqGUAX65s4LdJkr@thinkstation Signed-off-by: Zack Rusin <[email protected]> --- arch/x86/coco/tdx/tdx.c | 32 ++++++++++++++++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c index f904a636d449..4a683e9eafc3 100644 --- a/arch/x86/coco/tdx/tdx.c +++ b/arch/x86/coco/tdx/tdx.c @@ -4,6 +4,7 @@ #undef pr_fmt #define pr_fmt(fmt) "tdx: " fmt +#include <linux/cacheflush.h> #include <linux/cpufeature.h> #include <linux/export.h> #include <linux/io.h> @@ -18,6 +19,7 @@ #include <asm/paravirt_types.h> #include <asm/pgtable.h> +#include <asm/sections.h> #include <asm/set_memory.h> #include <asm/traps.h> /* MMIO direction */ @@ -1006,6 +1008,23 @@ static int tdx_enc_status_change_finish(unsigned long vaddr, int numpages, return 0; } +static char tdx_early_buffer[PAGE_SIZE] __initdata __aligned(PAGE_SIZE); + +static int __init tdx_early_decrypt_page(unsigned long addr, unsigned long alias) +{ + void *buffer = __va(__pa_symbol(tdx_early_buffer)); + int ret; + + memcpy(buffer, (void *)addr, PAGE_SIZE); + clflush_cache_range((void *)addr, PAGE_SIZE); + early_set_page_decrypted(addr, alias); + ret = tdx_enc_status_change_finish(addr, 1, false); + if (ret) + return ret; + memcpy((void *)addr, buffer, PAGE_SIZE); + return 0; +} + /* Stop new private<->shared conversions */ static void tdx_kexec_begin(void) { @@ -1033,6 +1052,18 @@ static void tdx_kexec_finish(void) lockdep_assert_irqs_disabled(); + /* Drop image aliases before the direct-map walk makes pages private. */ + addr = (unsigned long)_text; + while (addr < _brk_end) { + unsigned int level; + pte_t *pte = lookup_address(addr, &level); + + if (pte && pte_decrypted(*pte)) + set_pte(pte, __pte(0)); + addr = (addr & page_level_mask(level)) + page_level_size(level); + } + __flush_tlb_all(); + addr = PAGE_OFFSET; end = PAGE_OFFSET + get_max_mapped(); @@ -1160,6 +1191,7 @@ void __init tdx_early_init(void) */ x86_platform.guest.enc_status_change_prepare = tdx_enc_status_change_prepare; x86_platform.guest.enc_status_change_finish = tdx_enc_status_change_finish; + x86_init.paging.early_decrypt_page = tdx_early_decrypt_page; x86_platform.guest.enc_cache_flush_required = tdx_cache_flush_required; x86_platform.guest.enc_tlb_flush_required = tdx_tlb_flush_required; -- 2.53.0
