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[68.107.67.45]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-3286f7bf283sm41447470eec.8.2026.09.01.04.34.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Sep 2026 04:34:12 -0700 (PDT) From: "Jasmeet (Jazz) Bhatia" To: Ard Biesheuvel Cc: Ilias Apalodimas , rafael@kernel.org, Pavel Machek , linux-efi@vger.kernel.org, linux-pm@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org, "Jasmeet (Jazz) Bhatia" Subject: [PATCH v1 1/2] efi/libstub: Install memreserve table on x86 Date: Tue, 1 Sep 2026 04:34:07 -0700 Message-ID: <08dea57d1e1190a3dab0f6cd424c07a07b0760b8.1788259938.git.jasmeet.bhatia.us@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The generic EFI stub installs the Linux EFI memreserve configuration table from efi_stub_common(), but x86 uses a separate EFI stub path. Consequently, efi_mem_reserve_persistent() cannot be used on x86 when no memreserve root has been installed. Move install_memreserve_table() to the common stub helper code, expose it through efistub.h, and invoke it from the x86 stub before exiting boot services. This allows x86 kernels to add persistent EFI memory reservations that are carried across kexec. Signed-off-by: Jasmeet (Jazz) Bhatia --- .../firmware/efi/libstub/efi-stub-helper.c | 23 +++++++++++++++++++ drivers/firmware/efi/libstub/efi-stub.c | 23 ------------------- drivers/firmware/efi/libstub/efistub.h | 1 + drivers/firmware/efi/libstub/x86-stub.c | 2 ++ 4 files changed, 26 insertions(+), 23 deletions(-) diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c index f27f2e1f0019..9ea0ed0ed7d1 100644 --- a/drivers/firmware/efi/libstub/efi-stub-helper.c +++ b/drivers/firmware/efi/libstub/efi-stub-helper.c @@ -27,6 +27,29 @@ static bool efi_disable_pci_dma = IS_ENABLED(CONFIG_EFI_DISABLE_PCI_DMA); int efi_mem_encrypt; +void install_memreserve_table(void) +{ + struct linux_efi_memreserve *rsv; + efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID; + efi_status_t status; + + status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv), + (void **)&rsv); + if (status != EFI_SUCCESS) { + efi_err("Failed to allocate memreserve entry!\n"); + return; + } + + rsv->next = 0; + rsv->size = 0; + atomic_set(&rsv->count, 0); + + status = efi_bs_call(install_configuration_table, + &memreserve_table_guid, rsv); + if (status != EFI_SUCCESS) + efi_err("Failed to install memreserve config table!\n"); +} + bool __pure __efi_soft_reserve_enabled(void) { return !efi_nosoftreserve; diff --git a/drivers/firmware/efi/libstub/efi-stub.c b/drivers/firmware/efi/libstub/efi-stub.c index 42d6073bcd06..e378dd7db682 100644 --- a/drivers/firmware/efi/libstub/efi-stub.c +++ b/drivers/firmware/efi/libstub/efi-stub.c @@ -77,29 +77,6 @@ static struct sysfb_display_info *setup_primary_display(void) return NULL; } -static void install_memreserve_table(void) -{ - struct linux_efi_memreserve *rsv; - efi_guid_t memreserve_table_guid = LINUX_EFI_MEMRESERVE_TABLE_GUID; - efi_status_t status; - - status = efi_bs_call(allocate_pool, EFI_LOADER_DATA, sizeof(*rsv), - (void **)&rsv); - if (status != EFI_SUCCESS) { - efi_err("Failed to allocate memreserve entry!\n"); - return; - } - - rsv->next = 0; - rsv->size = 0; - atomic_set(&rsv->count, 0); - - status = efi_bs_call(install_configuration_table, - &memreserve_table_guid, rsv); - if (status != EFI_SUCCESS) - efi_err("Failed to install memreserve config table!\n"); -} - static u32 get_supported_rt_services(void) { const efi_rt_properties_table_t *rt_prop_table; diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h index fd91fc15ec81..8656d6a545e5 100644 --- a/drivers/firmware/efi/libstub/efistub.h +++ b/drivers/firmware/efi/libstub/efistub.h @@ -1168,6 +1168,7 @@ efi_enable_reset_attack_mitigation(void) { } #endif void efi_retrieve_eventlog(void); +void install_memreserve_table(void); struct sysfb_display_info *alloc_primary_display(void); struct sysfb_display_info *__alloc_primary_display(void); diff --git a/drivers/firmware/efi/libstub/x86-stub.c b/drivers/firmware/efi/libstub/x86-stub.c index cef32e2c82d8..4a24126ccfd9 100644 --- a/drivers/firmware/efi/libstub/x86-stub.c +++ b/drivers/firmware/efi/libstub/x86-stub.c @@ -1015,6 +1015,8 @@ void __noreturn efi_stub_entry(efi_handle_t handle, efi_retrieve_eventlog(); + install_memreserve_table(); + setup_graphics(boot_params); setup_efi_pci(boot_params); -- 2.55.0