From 3fb3f7164edc467450e650dca51dbe4823315a56 Mon Sep 17 00:00:00 2001 From: Samuel Holland Date: Tue, 27 Feb 2024 22:55:33 -0800 Subject: riscv: Fix enabling cbo.zero when running in M-mode When the kernel is running in M-mode, the CBZE bit must be set in the menvcfg CSR, not in senvcfg. Cc: Fixes: 43c16d51a19b ("RISC-V: Enable cbo.zero in usermode") Reviewed-by: Andrew Jones Signed-off-by: Samuel Holland Reviewed-by: Conor Dooley Link: https://lore.kernel.org/r/20240228065559.3434837-2-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt --- arch/riscv/include/asm/csr.h | 2 ++ arch/riscv/kernel/cpufeature.c | 2 +- 2 files changed, 3 insertions(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/riscv/include/asm/csr.h b/arch/riscv/include/asm/csr.h index 510014051f5d..2468c55933cd 100644 --- a/arch/riscv/include/asm/csr.h +++ b/arch/riscv/include/asm/csr.h @@ -424,6 +424,7 @@ # define CSR_STATUS CSR_MSTATUS # define CSR_IE CSR_MIE # define CSR_TVEC CSR_MTVEC +# define CSR_ENVCFG CSR_MENVCFG # define CSR_SCRATCH CSR_MSCRATCH # define CSR_EPC CSR_MEPC # define CSR_CAUSE CSR_MCAUSE @@ -448,6 +449,7 @@ # define CSR_STATUS CSR_SSTATUS # define CSR_IE CSR_SIE # define CSR_TVEC CSR_STVEC +# define CSR_ENVCFG CSR_SENVCFG # define CSR_SCRATCH CSR_SSCRATCH # define CSR_EPC CSR_SEPC # define CSR_CAUSE CSR_SCAUSE diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c index 89920f84d0a3..c5b13f7dd482 100644 --- a/arch/riscv/kernel/cpufeature.c +++ b/arch/riscv/kernel/cpufeature.c @@ -950,7 +950,7 @@ arch_initcall(check_unaligned_access_all_cpus); void riscv_user_isa_enable(void) { if (riscv_cpu_has_extension_unlikely(smp_processor_id(), RISCV_ISA_EXT_ZICBOZ)) - csr_set(CSR_SENVCFG, ENVCFG_CBZE); + csr_set(CSR_ENVCFG, ENVCFG_CBZE); } #ifdef CONFIG_RISCV_ALTERNATIVE -- cgit v1.2.3 From 4774848fef6041716a4883217eb75f6b10eb183b Mon Sep 17 00:00:00 2001 From: Samuel Holland Date: Tue, 27 Feb 2024 22:55:34 -0800 Subject: riscv: Add a custom ISA extension for the [ms]envcfg CSR The [ms]envcfg CSR was added in version 1.12 of the RISC-V privileged ISA (aka S[ms]1p12). However, bits in this CSR are defined by several other extensions which may be implemented separately from any particular version of the privileged ISA (for example, some unrelated errata may prevent an implementation from claiming conformance with Ss1p12). As a result, Linux cannot simply use the privileged ISA version to determine if the CSR is present. It must also check if any of these other extensions are implemented. It also cannot probe the existence of the CSR at runtime, because Linux does not require Sstrict, so (in the absence of additional information) it cannot know if a CSR at that address is [ms]envcfg or part of some non-conforming vendor extension. Since there are several standard extensions that imply the existence of the [ms]envcfg CSR, it becomes unwieldy to check for all of them wherever the CSR is accessed. Instead, define a custom Xlinuxenvcfg ISA extension bit that is implied by the other extensions and denotes that the CSR exists as defined in the privileged ISA, containing at least one of the fields common between menvcfg and senvcfg. This extension does not need to be parsed from the devicetree or ISA string because it can only be implemented as a subset of some other standard extension. Cc: # v6.7+ Signed-off-by: Samuel Holland Reviewed-by: Conor Dooley Reviewed-by: Andrew Jones Link: https://lore.kernel.org/r/20240228065559.3434837-3-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt --- arch/riscv/include/asm/hwcap.h | 2 ++ arch/riscv/kernel/cpufeature.c | 14 ++++++++++++-- 2 files changed, 14 insertions(+), 2 deletions(-) (limited to 'arch') diff --git a/arch/riscv/include/asm/hwcap.h b/arch/riscv/include/asm/hwcap.h index 5340f818746b..1f2d2599c655 100644 --- a/arch/riscv/include/asm/hwcap.h +++ b/arch/riscv/include/asm/hwcap.h @@ -81,6 +81,8 @@ #define RISCV_ISA_EXT_ZTSO 72 #define RISCV_ISA_EXT_ZACAS 73 +#define RISCV_ISA_EXT_XLINUXENVCFG 127 + #define RISCV_ISA_EXT_MAX 128 #define RISCV_ISA_EXT_INVALID U32_MAX diff --git a/arch/riscv/kernel/cpufeature.c b/arch/riscv/kernel/cpufeature.c index c5b13f7dd482..dacffef68ce2 100644 --- a/arch/riscv/kernel/cpufeature.c +++ b/arch/riscv/kernel/cpufeature.c @@ -201,6 +201,16 @@ static const unsigned int riscv_zvbb_exts[] = { RISCV_ISA_EXT_ZVKB }; +/* + * While the [ms]envcfg CSRs were not defined until version 1.12 of the RISC-V + * privileged ISA, the existence of the CSRs is implied by any extension which + * specifies [ms]envcfg bit(s). Hence, we define a custom ISA extension for the + * existence of the CSR, and treat it as a subset of those other extensions. + */ +static const unsigned int riscv_xlinuxenvcfg_exts[] = { + RISCV_ISA_EXT_XLINUXENVCFG +}; + /* * The canonical order of ISA extension names in the ISA string is defined in * chapter 27 of the unprivileged specification. @@ -250,8 +260,8 @@ const struct riscv_isa_ext_data riscv_isa_ext[] = { __RISCV_ISA_EXT_DATA(c, RISCV_ISA_EXT_c), __RISCV_ISA_EXT_DATA(v, RISCV_ISA_EXT_v), __RISCV_ISA_EXT_DATA(h, RISCV_ISA_EXT_h), - __RISCV_ISA_EXT_DATA(zicbom, RISCV_ISA_EXT_ZICBOM), - __RISCV_ISA_EXT_DATA(zicboz, RISCV_ISA_EXT_ZICBOZ), + __RISCV_ISA_EXT_SUPERSET(zicbom, RISCV_ISA_EXT_ZICBOM, riscv_xlinuxenvcfg_exts), + __RISCV_ISA_EXT_SUPERSET(zicboz, RISCV_ISA_EXT_ZICBOZ, riscv_xlinuxenvcfg_exts), __RISCV_ISA_EXT_DATA(zicntr, RISCV_ISA_EXT_ZICNTR), __RISCV_ISA_EXT_DATA(zicond, RISCV_ISA_EXT_ZICOND), __RISCV_ISA_EXT_DATA(zicsr, RISCV_ISA_EXT_ZICSR), -- cgit v1.2.3 From 05ab803d1ad8ac505ade77c6bd3f86b1b4ea0dc4 Mon Sep 17 00:00:00 2001 From: Samuel Holland Date: Tue, 27 Feb 2024 22:55:35 -0800 Subject: riscv: Save/restore envcfg CSR during CPU suspend The value of the [ms]envcfg CSR is lost when entering a nonretentive idle state, so the CSR must be rewritten when resuming the CPU. Cc: # v6.7+ Fixes: 43c16d51a19b ("RISC-V: Enable cbo.zero in usermode") Signed-off-by: Samuel Holland Reviewed-by: Conor Dooley Reviewed-by: Andrew Jones Link: https://lore.kernel.org/r/20240228065559.3434837-4-samuel.holland@sifive.com Signed-off-by: Palmer Dabbelt --- arch/riscv/include/asm/suspend.h | 1 + arch/riscv/kernel/suspend.c | 4 ++++ 2 files changed, 5 insertions(+) (limited to 'arch') diff --git a/arch/riscv/include/asm/suspend.h b/arch/riscv/include/asm/suspend.h index 02f87867389a..491296a335d0 100644 --- a/arch/riscv/include/asm/suspend.h +++ b/arch/riscv/include/asm/suspend.h @@ -14,6 +14,7 @@ struct suspend_context { struct pt_regs regs; /* Saved and restored by high-level functions */ unsigned long scratch; + unsigned long envcfg; unsigned long tvec; unsigned long ie; #ifdef CONFIG_MMU diff --git a/arch/riscv/kernel/suspend.c b/arch/riscv/kernel/suspend.c index 239509367e42..299795341e8a 100644 --- a/arch/riscv/kernel/suspend.c +++ b/arch/riscv/kernel/suspend.c @@ -15,6 +15,8 @@ void suspend_save_csrs(struct suspend_context *context) { context->scratch = csr_read(CSR_SCRATCH); + if (riscv_cpu_has_extension_unlikely(smp_processor_id(), RISCV_ISA_EXT_XLINUXENVCFG)) + context->envcfg = csr_read(CSR_ENVCFG); context->tvec = csr_read(CSR_TVEC); context->ie = csr_read(CSR_IE); @@ -36,6 +38,8 @@ void suspend_save_csrs(struct suspend_context *context) void suspend_restore_csrs(struct suspend_context *context) { csr_write(CSR_SCRATCH, context->scratch); + if (riscv_cpu_has_extension_unlikely(smp_processor_id(), RISCV_ISA_EXT_XLINUXENVCFG)) + csr_write(CSR_ENVCFG, context->envcfg); csr_write(CSR_TVEC, context->tvec); csr_write(CSR_IE, context->ie); -- cgit v1.2.3