From: Ard Biesheuvel <ardb+git@google.com>
To: linux-kernel@vger.kernel.org
Cc: linux-efi@vger.kernel.org, x86@kernel.org,
Ard Biesheuvel <ardb@kernel.org>,
"Mike Rapoport (Microsoft)" <rppt@kernel.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: [PATCH v2 06/19] x86/efi: Defer sub-1M check from unmap to free stage
Date: Thu, 19 Mar 2026 10:05:36 +0100 [thread overview]
Message-ID: <20260319090529.1091660-27-ardb+git@google.com> (raw)
In-Reply-To: <20260319090529.1091660-21-ardb+git@google.com>
From: Ard Biesheuvel <ardb@kernel.org>
As a first step towards moving the free logic to a later stage
altogether, and only keeping the unmap and the realmode trampoline hack
during the early stage of freeing the boot service code and data
regions, move the logic that avoids freeing memory below 1M to the later
stage.
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
---
arch/x86/platform/efi/quirks.c | 24 +++++++++-----------
1 file changed, 11 insertions(+), 13 deletions(-)
diff --git a/arch/x86/platform/efi/quirks.c b/arch/x86/platform/efi/quirks.c
index 906e29754026..25f51d673ad6 100644
--- a/arch/x86/platform/efi/quirks.c
+++ b/arch/x86/platform/efi/quirks.c
@@ -475,18 +475,6 @@ void __init efi_unmap_boot_services(void)
size -= rm_size;
}
- /*
- * Don't free memory under 1M for two reasons:
- * - BIOS might clobber it
- * - Crash kernel needs it to be reserved
- */
- if (start + size < SZ_1M)
- continue;
- if (start < SZ_1M) {
- size -= (SZ_1M - start);
- start = SZ_1M;
- }
-
/*
* With CONFIG_DEFERRED_STRUCT_PAGE_INIT parts of the memory
* map are still not initialized and we can't reliably free
@@ -579,7 +567,17 @@ static int __init efi_free_boot_services(void)
return 0;
while (range->start) {
- freed += efi_free_unreserved_subregions(range->start, range->end);
+ /*
+ * Don't free memory under 1M for two reasons:
+ * - BIOS might clobber it
+ * - Crash kernel needs it to be reserved
+ */
+ u64 start = max(range->start, SZ_1M);
+
+ if (start >= range->end)
+ continue;
+
+ freed += efi_free_unreserved_subregions(start, range->end);
range++;
}
kfree(ranges_to_free);
--
2.53.0.851.ga537e3e6e9-goog
next prev parent reply other threads:[~2026-03-19 9:06 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-19 9:05 [PATCH v2 00/19] efi/x86: Avoid the need to mangle the EFI memory map Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 01/19] memblock: Permit existing reserved regions to be marked RSRV_KERN Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 02/19] efi: Tag memblock reservations of boot services regions as RSRV_KERN Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 03/19] x86/efi: Unmap kernel-reserved boot regions from EFI page tables Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 04/19] x86/efi: Drop EFI_MEMORY_RUNTIME check from __ioremap_check_other() Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 05/19] x86/efi: Omit RSRV_KERN memblock reservations when freeing boot regions Ard Biesheuvel
2026-03-19 9:05 ` Ard Biesheuvel [this message]
2026-03-19 9:05 ` [PATCH v2 07/19] x86/efi: Simplify real mode trampoline allocation quirk Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 08/19] x86/efi: Omit redundant kernel image overlap check Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 09/19] x86/efi: Drop redundant EFI_PARAVIRT check Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 10/19] x86/efi: Do not rely on EFI_MEMORY_RUNTIME bit and avoid entry splitting Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 11/19] efi: Use nr_map not map_end to find the last valid memory map entry Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 12/19] x86/efi: Only merge EFI memory map entries on 32-bit systems Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 13/19] x86/efi: Clean the memory map using iterator and filter API Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 14/19] x86/efi: Update the runtime map in place Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 15/19] x86/efi: Use iterator API when mapping EFI regions for runtime Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 16/19] x86/efi: Reuse memory map instead of reallocating it Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 17/19] x86/efi: Defer compaction of the EFI memory map Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 18/19] x86/efi: Do not abuse RUNTIME bit to mark boot regions as reserved Ard Biesheuvel
2026-03-19 9:05 ` [PATCH v2 19/19] x86/efi: Free unused tail of the EFI memory map Ard Biesheuvel
2026-03-24 9:50 ` [PATCH v2 00/19] efi/x86: Avoid the need to mangle " Ard Biesheuvel
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