On Wed, Aug 2, 2023 at 4:14 AM Conor Dooley conor.dooley@microchip.com wrote:
Add an erratum for versions [v0.8 to v1.3) of OpenSBI which fail to add the "no-map" property to the reserved memory nodes for the regions it has protected using PMPs.
Our existing fix sweeping hibernation under the carpet by marking it NONPORTABLE is insufficient as there are other ways to generate accesses to these reserved memory regions, as Petr discovered [1] while testing crash kernels & kdump.
Intercede during the boot process when the afflicted versions of OpenSBI are present & set the "no-map" property in all "mmode_resv" nodes before the kernel does its reserved memory region initialisation.
We have different mechanisms of DT being passed to the kernel.
1. A prior stage(e.g U-Boot SPL) to M-mode runtime firmware (e.g. OpenSBI, rustSBI) passes the DT to M-mode runtime firmware and it passes to the next stage. In this case, M-mode runtime firmware gets a chance to update the no-map property in DT that the kernel can parse.
2. User loads the DT from the boot loader (e.g EDK2, U-Boot proper). Any DT patching done by the M-mode firmware is useless. If these DTBs don't have the no-map property, hibernation or EFI booting will have issues as well.
We are trying to solve only one part of problem #1 in this patch. I don't think any other M-mode runtime firmware patches DT with no-map property as well. Please let me know if I am wrong about that. The problem is not restricted to [v0.8 to v1.3) of OpenSBI.
The booting doc now says that no-map property must be set and any usage of DTBs without that (via #1 or #2) will have unintended consequences.
Reported-by: Song Shuai suagrfillet@gmail.com Link: https://lore.kernel.org/all/CAAYs2=gQvkhTeioMmqRDVGjdtNF_vhB+vm_1dHJxPNi75YD... Reported-by: JeeHeng Sia jeeheng.sia@starfivetech.com Link: https://groups.google.com/a/groups.riscv.org/g/sw-dev/c/ITXwaKfA6z8 Reported-by: Petr Tesarik petrtesarik@huaweicloud.com Closes: https://lore.kernel.org/linux-riscv/76ff0f51-d6c1-580d-f943-061e93073306@hua... [1] CC: stable@vger.kernel.org Signed-off-by: Conor Dooley conor.dooley@microchip.com
arch/riscv/include/asm/sbi.h | 5 +++++ arch/riscv/kernel/sbi.c | 42 +++++++++++++++++++++++++++++++++++- arch/riscv/mm/init.c | 3 +++ 3 files changed, 49 insertions(+), 1 deletion(-)
diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h index 5b4a1bf5f439..5360f3476278 100644 --- a/arch/riscv/include/asm/sbi.h +++ b/arch/riscv/include/asm/sbi.h @@ -252,6 +252,9 @@ enum sbi_pmu_ctr_type { #define SBI_ERR_ALREADY_STARTED -7 #define SBI_ERR_ALREADY_STOPPED -8
+/* SBI implementation IDs */ +#define SBI_IMP_OPENSBI 1
extern unsigned long sbi_spec_version; struct sbiret { long error; @@ -259,6 +262,8 @@ struct sbiret { };
void sbi_init(void); +void sbi_apply_reserved_mem_erratum(void *dtb_va);
struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0, unsigned long arg1, unsigned long arg2, unsigned long arg3, unsigned long arg4, diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c index c672c8ba9a2a..aeb27263fa53 100644 --- a/arch/riscv/kernel/sbi.c +++ b/arch/riscv/kernel/sbi.c @@ -5,8 +5,10 @@
- Copyright (c) 2020 Western Digital Corporation or its affiliates.
*/
+#include <linux/acpi.h> #include <linux/bits.h> #include <linux/init.h> +#include <linux/libfdt.h> #include <linux/pm.h> #include <linux/reboot.h> #include <asm/sbi.h> @@ -583,6 +585,40 @@ long sbi_get_mimpid(void) } EXPORT_SYMBOL_GPL(sbi_get_mimpid);
+static long sbi_firmware_id; +static long sbi_firmware_version;
+/*
- For devicetrees patched by OpenSBI a "mmode_resv" node is added to cover
- the region OpenSBI has protected by means of a PMP. Some versions of OpenSBI,
- [v0.8 to v1.3), omitted the "no-map" property, but this trips up hibernation
- among other things.
- */
+void __init sbi_apply_reserved_mem_erratum(void *dtb_pa) +{
int child, reserved_mem;if (sbi_firmware_id != SBI_IMP_OPENSBI)return;if (!acpi_disabled)return;if (sbi_firmware_version >= 0x10003 || sbi_firmware_version < 0x8)return;reserved_mem = fdt_path_offset((void *)dtb_pa, "/reserved-memory");if (reserved_mem < 0)return;fdt_for_each_subnode(child, (void *)dtb_pa, reserved_mem) {const char *name = fdt_get_name((void *)dtb_pa, child, NULL);if (!strncmp(name, "mmode_resv", 10))fdt_setprop((void *)dtb_pa, child, "no-map", NULL, 0);}+};
void __init sbi_init(void) { int ret; @@ -596,8 +632,12 @@ void __init sbi_init(void) sbi_major_version(), sbi_minor_version());
if (!sbi_spec_is_0_1()) {
sbi_firmware_id = sbi_get_firmware_id();sbi_firmware_version = sbi_get_firmware_version();pr_info("SBI implementation ID=0x%lx Version=0x%lx\n",
sbi_get_firmware_id(), sbi_get_firmware_version());
sbi_firmware_id, sbi_firmware_version);if (sbi_probe_extension(SBI_EXT_TIME)) { __sbi_set_timer = __sbi_set_timer_v02; pr_info("SBI TIME extension detected\n");diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c index 70fb31960b63..cb16bfdeacdb 100644 --- a/arch/riscv/mm/init.c +++ b/arch/riscv/mm/init.c @@ -29,6 +29,7 @@ #include <asm/tlbflush.h> #include <asm/sections.h> #include <asm/soc.h> +#include <asm/sbi.h> #include <asm/io.h> #include <asm/ptdump.h> #include <asm/numa.h> @@ -253,6 +254,8 @@ static void __init setup_bootmem(void) * in the device tree, otherwise the allocation could end up in a * reserved region. */
sbi_apply_reserved_mem_erratum(dtb_early_va); early_init_fdt_scan_reserved_mem(); /*-- 2.40.1