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d54d610243
Communicating with the hypervisor using the shared GHCB page requires
clearing the C bit in the mapping of that page. When executing in the
context of the EFI boot services, the page tables are owned by the
firmware, and this manipulation is not possible.
So switch to a different API for accepting memory in SEV-SNP guests, one
which is actually supported at the point during boot where the EFI stub
may need to accept memory, but the SEV-SNP init code has not executed
yet.
For simplicity, also switch the memory acceptance carried out by the
decompressor when not booting via EFI - this only involves the
allocation for the decompressed kernel, and is generally only called
after kexec, as normal boot will jump straight into the kernel from the
EFI stub.
Fixes: 6c3211796326 ("x86/sev: Add SNP-specific unaccepted memory support")
Tested-by: Tom Lendacky <thomas.lendacky@amd.com>
Co-developed-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: <stable@vger.kernel.org>
Cc: Dionna Amalie Glaze <dionnaglaze@google.com>
Cc: Kevin Loughlin <kevinloughlin@google.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-efi@vger.kernel.org
Link: https://lore.kernel.org/r/20250404082921.2767593-8-ardb+git@google.com # discussion thread #1
Link: https://lore.kernel.org/r/20250410132850.3708703-2-ardb+git@google.com # discussion thread #2
Link: https://lore.kernel.org/r/20250417202120.1002102-2-ardb+git@google.com # final submission
90 lines
2.1 KiB
C
90 lines
2.1 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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#include "error.h"
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#include "misc.h"
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#include "tdx.h"
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#include "sev.h"
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#include <asm/shared/tdx.h>
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/*
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* accept_memory() and process_unaccepted_memory() called from EFI stub which
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* runs before decompressor and its early_tdx_detect().
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*
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* Enumerate TDX directly from the early users.
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*/
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static bool early_is_tdx_guest(void)
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{
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static bool once;
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static bool is_tdx;
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if (!IS_ENABLED(CONFIG_INTEL_TDX_GUEST))
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return false;
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if (!once) {
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u32 eax, sig[3];
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cpuid_count(TDX_CPUID_LEAF_ID, 0, &eax,
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&sig[0], &sig[2], &sig[1]);
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is_tdx = !memcmp(TDX_IDENT, sig, sizeof(sig));
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once = true;
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}
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return is_tdx;
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}
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void arch_accept_memory(phys_addr_t start, phys_addr_t end)
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{
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static bool sevsnp;
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/* Platform-specific memory-acceptance call goes here */
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if (early_is_tdx_guest()) {
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if (!tdx_accept_memory(start, end))
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panic("TDX: Failed to accept memory\n");
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} else if (sevsnp || (sev_get_status() & MSR_AMD64_SEV_SNP_ENABLED)) {
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sevsnp = true;
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snp_accept_memory(start, end);
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} else {
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error("Cannot accept memory: unknown platform\n");
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}
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}
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bool init_unaccepted_memory(void)
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{
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guid_t guid = LINUX_EFI_UNACCEPTED_MEM_TABLE_GUID;
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struct efi_unaccepted_memory *table;
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unsigned long cfg_table_pa;
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unsigned int cfg_table_len;
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enum efi_type et;
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int ret;
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et = efi_get_type(boot_params_ptr);
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if (et == EFI_TYPE_NONE)
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return false;
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ret = efi_get_conf_table(boot_params_ptr, &cfg_table_pa, &cfg_table_len);
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if (ret) {
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warn("EFI config table not found.");
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return false;
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}
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table = (void *)efi_find_vendor_table(boot_params_ptr, cfg_table_pa,
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cfg_table_len, guid);
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if (!table)
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return false;
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if (table->version != 1)
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error("Unknown version of unaccepted memory table\n");
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/*
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* In many cases unaccepted_table is already set by EFI stub, but it
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* has to be initialized again to cover cases when the table is not
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* allocated by EFI stub or EFI stub copied the kernel image with
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* efi_relocate_kernel() before the variable is set.
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*
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* It must be initialized before the first usage of accept_memory().
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*/
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unaccepted_table = table;
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return true;
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}
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