Re: [PATCH -fixes 1/2] riscv: Fix enabling cbo.zero when running in M-mode

From: Andrew Jones
Date: Mon Feb 12 2024 - 04:51:01 EST


On Sun, Feb 11, 2024 at 06:26:14PM -0800, Samuel Holland wrote:
> When the kernel is running in M-mode, the CBZE bit must be set in the
> menvcfg CSR, not in senvcfg.
>
> Cc: stable@xxxxxxxxxx
> Fixes: 43c16d51a19b ("RISC-V: Enable cbo.zero in usermode")
> Signed-off-by: Samuel Holland <samuel.holland@xxxxxxxxxx>
> ---
>
> arch/riscv/include/asm/csr.h | 2 ++
> arch/riscv/kernel/cpufeature.c | 2 +-
> 2 files changed, 3 insertions(+), 1 deletion(-)
>
> 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
> --
> 2.43.0
>

Deepak has also posted this change[1], but his is missing the Fixes tag.

[1] https://lore.kernel.org/all/20240125024611.1321941-1-debug@xxxxxxxxxxxx/

Thanks,
drew