From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1hPzzk-0003Hx-P5 for kexec@lists.infradead.org; Mon, 13 May 2019 01:43:14 +0000 Date: Mon, 13 May 2019 09:43:05 +0800 From: Baoquan He Subject: Re: [PATCH v6 1/2] x86/kexec: Build identity mapping for EFI systab and ACPI tables Message-ID: <20190513014248.GA16774@MiWiFi-R3L-srv> References: <20190424092944.30481-1-bhe@redhat.com> <20190424092944.30481-2-bhe@redhat.com> <20190429002318.GA25400@MiWiFi-R3L-srv> <20190429135536.GC2324@zn.tnic> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190429135536.GC2324@zn.tnic> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Borislav Petkov Cc: fanc.fnst@cn.fujitsu.com, kasong@redhat.com, x86@kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, hpa@zytor.com, j-nomura@ce.jp.nec.com, tglx@linutronix.de, dyoung@redhat.com Hi Boris, On 04/29/19 at 03:55pm, Borislav Petkov wrote: > From: Kairui Song > Date: Mon, 29 Apr 2019 08:23:18 +0800 > Subject: [PATCH] x86/kexec: Add the EFI system tables and ACPI tables to the ident map > > Currently, only the whole physical memory is identity-mapped for the > kexec kernel and the regions reserved by firmware are ignored. > > However, the recent addition of RSDP parsing in the decompression stage > and especially: > > 33f0df8d843d ("x86/boot: Search for RSDP in the EFI tables") > > which tries to access EFI system tables and to dig out the RDSP address > from there, becomes a problem because in certain configurations, they > might not be mapped in the kexec'ed kernel's address space. > > What is more, this problem doesn't appear on all systems because the > kexec kernel uses gigabyte pages to build the identity mapping. And > the EFI system tables and ACPI tables can, depending on the system > configuration, end up being mapped as part of all physical memory, if > they share the same 1 GB area with the physical memory. > > Therefore, make sure they're always mapped. > > [ bp: productize half-baked patch: > - rewrite commit message. > - s/init_acpi_pgtable/map_acpi_tables/ in the !ACPI case. ] Can this patchset be merged, or picked into tip? Thanks Baoquan > Signed-off-by: Kairui Song > Signed-off-by: Baoquan He > Signed-off-by: Borislav Petkov > Cc: dyoung@redhat.com > Cc: fanc.fnst@cn.fujitsu.com > Cc: "H. Peter Anvin" > Cc: Ingo Molnar > Cc: j-nomura@ce.jp.nec.com > Cc: kexec@lists.infradead.org > Cc: "Kirill A. Shutemov" > Cc: Lianbo Jiang > Cc: Tetsuo Handa > Cc: Thomas Gleixner > Cc: x86-ml > Link: https://lkml.kernel.org/r/20190429002318.GA25400@MiWiFi-R3L-srv > --- > arch/x86/kernel/machine_kexec_64.c | 75 ++++++++++++++++++++++++++++++ > 1 file changed, 75 insertions(+) > > diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c > index ceba408ea982..3c77bdf7b32a 100644 > --- a/arch/x86/kernel/machine_kexec_64.c > +++ b/arch/x86/kernel/machine_kexec_64.c > @@ -18,6 +18,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -29,6 +30,43 @@ > #include > #include > > +#ifdef CONFIG_ACPI > +/* > + * Used while adding mapping for ACPI tables. > + * Can be reused when other iomem regions need be mapped > + */ > +struct init_pgtable_data { > + struct x86_mapping_info *info; > + pgd_t *level4p; > +}; > + > +static int mem_region_callback(struct resource *res, void *arg) > +{ > + struct init_pgtable_data *data = arg; > + unsigned long mstart, mend; > + > + mstart = res->start; > + mend = mstart + resource_size(res) - 1; > + > + return kernel_ident_mapping_init(data->info, data->level4p, mstart, mend); > +} > + > +static int > +map_acpi_tables(struct x86_mapping_info *info, pgd_t *level4p) > +{ > + unsigned long flags = IORESOURCE_MEM | IORESOURCE_BUSY; > + struct init_pgtable_data data; > + > + data.info = info; > + data.level4p = level4p; > + flags = IORESOURCE_MEM | IORESOURCE_BUSY; > + return walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1, > + &data, mem_region_callback); > +} > +#else > +static int map_acpi_tables(struct x86_mapping_info *info, pgd_t *level4p) { return 0; } > +#endif > + > #ifdef CONFIG_KEXEC_FILE > const struct kexec_file_ops * const kexec_file_loaders[] = { > &kexec_bzImage64_ops, > @@ -36,6 +74,31 @@ const struct kexec_file_ops * const kexec_file_loaders[] = { > }; > #endif > > +static int > +map_efi_systab(struct x86_mapping_info *info, pgd_t *level4p) > +{ > +#ifdef CONFIG_EFI > + unsigned long mstart, mend; > + > + if (!efi_enabled(EFI_BOOT)) > + return 0; > + > + mstart = (boot_params.efi_info.efi_systab | > + ((u64)boot_params.efi_info.efi_systab_hi<<32)); > + > + if (efi_enabled(EFI_64BIT)) > + mend = mstart + sizeof(efi_system_table_64_t); > + else > + mend = mstart + sizeof(efi_system_table_32_t); > + > + if (!mstart) > + return 0; > + > + return kernel_ident_mapping_init(info, level4p, mstart, mend); > +#endif > + return 0; > +} > + > static void free_transition_pgtable(struct kimage *image) > { > free_page((unsigned long)image->arch.p4d); > @@ -159,6 +222,18 @@ static int init_pgtable(struct kimage *image, unsigned long start_pgtable) > return result; > } > > + /* > + * Prepare EFI systab and ACPI tables for kexec kernel since they are > + * not covered by pfn_mapped. > + */ > + result = map_efi_systab(&info, level4p); > + if (result) > + return result; > + > + result = map_acpi_tables(&info, level4p); > + if (result) > + return result; > + > return init_transition_pgtable(image, level4p); > } > > -- > 2.21.0 > > -- > Regards/Gruss, > Boris. > > Good mailing practices for 400: avoid top-posting and trim the reply. _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec