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[2a03:2880:20ff:1::face:b00c]) by smtp.gmail.com with ESMTPSA id af79cd13be357-7a9a79455b1sm407594885a.19.2024.09.11.03.41.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Sep 2024 03:41:11 -0700 (PDT) From: Usama Arif To: linux-efi@vger.kernel.org, devel@edk2.groups.io, kexec@lists.infradead.org Cc: ardb@kernel.org, ebiederm@xmission.com, bhe@redhat.com, vgoyal@redhat.com, tglx@linutronix.de, dave.hansen@linux.intel.com, x86@kernel.org, linux-kernel@vger.kernel.org, leitao@debian.org, rmikey@meta.com, gourry@gourry.net, Usama Arif Subject: [RFC] efi/tpm: add efi.tpm_log as a reserved region in 820_table_firmware Date: Wed, 11 Sep 2024 11:41:08 +0100 Message-ID: <20240911104109.1831501-1-usamaarif642@gmail.com> X-Mailer: git-send-email 2.43.5 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Looking at the TPM spec [1] If the ACPI TPM2 table contains the address and size of the Platform Firmware TCG log, firmware =E2=80=9Cpins=E2=80=9D the memory associated wit= h the Platform FirmwareTCG log, and reports this memory as =E2=80=9CReserved=E2= =80=9D memory via the INT 15h/E820 interface. It looks like the firmware should pass this as reserved in e820 memory map. However, it doesn't seem to. The firmware being tested on is: dmidecode -s bios-version edk2-20240214-2.el9 When this area is not reserved, it comes up as usable in /sys/firmware/memmap. This means that kexec, which uses that memmap to find usable memory regions, can select the region where efi.tpm_log is and overwrite it and relocate_kernel. Having a fix in firmware can be difficult to get through. As a secondary fix, this patch marks that region as reserved in e820_table_firmware if it is currently E820_TYPE_RAM so that kexec doesn't use it for kernel segments. [1] https://trustedcomputinggroup.org/wp-content/uploads/PC-ClientPlatform_= Profile_for_TPM_2p0_Systems_v49_161114_public-review.pdf Signed-off-by: Usama Arif Reported-by: Breno Leitao --- arch/x86/include/asm/e820/api.h | 2 ++ arch/x86/kernel/e820.c | 6 ++++++ arch/x86/platform/efi/efi.c | 9 +++++++++ drivers/firmware/efi/tpm.c | 2 +- include/linux/efi.h | 7 +++++++ 5 files changed, 25 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/e820/api.h b/arch/x86/include/asm/e820/ap= i.h index 2e74a7f0e935..4e9aa24f03bd 100644 --- a/arch/x86/include/asm/e820/api.h +++ b/arch/x86/include/asm/e820/api.h @@ -16,6 +16,8 @@ extern bool e820__mapped_all(u64 start, u64 end, enum e82= 0_type type); =20 extern void e820__range_add (u64 start, u64 size, enum e820_type type); extern u64 e820__range_update(u64 start, u64 size, enum e820_type old_typ= e, enum e820_type new_type); +extern u64 e820__range_update_firmware(u64 start, u64 size, enum e820_typ= e old_type, + enum e820_type new_type); extern u64 e820__range_remove(u64 start, u64 size, enum e820_type old_typ= e, bool check_type); extern u64 e820__range_update_table(struct e820_table *t, u64 start, u64 = size, enum e820_type old_type, enum e820_type new_type); =20 diff --git a/arch/x86/kernel/e820.c b/arch/x86/kernel/e820.c index 4893d30ce438..912400161623 100644 --- a/arch/x86/kernel/e820.c +++ b/arch/x86/kernel/e820.c @@ -538,6 +538,12 @@ u64 __init e820__range_update_table(struct e820_table = *t, u64 start, u64 size, return __e820__range_update(t, start, size, old_type, new_type); } =20 +u64 __init e820__range_update_firmware(u64 start, u64 size, enum e820_type= old_type, + enum e820_type new_type) +{ + return __e820__range_update(e820_table_firmware, start, size, old_type, n= ew_type); +} + /* Remove a range of memory from the E820 table: */ u64 __init e820__range_remove(u64 start, u64 size, enum e820_type old_type= , bool check_type) { diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c index 88a96816de9a..aa95f77d7a30 100644 --- a/arch/x86/platform/efi/efi.c +++ b/arch/x86/platform/efi/efi.c @@ -171,6 +171,15 @@ static void __init do_add_efi_memmap(void) e820__update_table(e820_table); } =20 +/* Reserve firmware area if it was marked as RAM */ +void arch_update_firmware_area(u64 addr, u64 size) +{ + if (e820__get_entry_type(addr, addr + size) =3D=3D E820_TYPE_RAM) { + e820__range_update_firmware(addr, size, E820_TYPE_RAM, E820_TYPE_RESERVE= D); + e820__update_table(e820_table_firmware); + } +} + /* * Given add_efi_memmap defaults to 0 and there is no alternative * e820 mechanism for soft-reserved memory, import the full EFI memory diff --git a/drivers/firmware/efi/tpm.c b/drivers/firmware/efi/tpm.c index e8d69bd548f3..8e6e7131d718 100644 --- a/drivers/firmware/efi/tpm.c +++ b/drivers/firmware/efi/tpm.c @@ -60,6 +60,7 @@ int __init efi_tpm_eventlog_init(void) } =20 tbl_size =3D sizeof(*log_tbl) + log_tbl->size; + arch_update_firmware_area(efi.tpm_log, tbl_size); memblock_reserve(efi.tpm_log, tbl_size); =20 if (efi.tpm_final_log =3D=3D EFI_INVALID_TABLE_ADDR) { @@ -107,4 +108,3 @@ int __init efi_tpm_eventlog_init(void) early_memunmap(log_tbl, sizeof(*log_tbl)); return ret; } - diff --git a/include/linux/efi.h b/include/linux/efi.h index 6bf3c4fe8511..9c239cdff771 100644 --- a/include/linux/efi.h +++ b/include/linux/efi.h @@ -1371,4 +1371,11 @@ extern struct blocking_notifier_head efivar_ops_nh; void efivars_generic_ops_register(void); void efivars_generic_ops_unregister(void); =20 +#ifdef CONFIG_X86_64 +void __init arch_update_firmware_area(u64 addr, u64 size); +#else +static inline void __init arch_update_firmware_area(u64 addr, u64 size) +{ +} +#endif #endif /* _LINUX_EFI_H */ --=20 2.43.5