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: <stable@vger.kernel.org> # v6.7+
Fixes: 43c16d51a19b ("RISC-V: Enable cbo.zero in usermode")
Signed-off-by: Samuel Holland <samuel.holland@sifive.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Reviewed-by: Andrew Jones <ajones@ventanamicro.com>
Link: https://lore.kernel.org/r/20240228065559.3434837-4-samuel.holland@sifive.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>

diff --git a/arch/riscv/include/asm/suspend.h b/arch/riscv/include/asm/suspend.h
index 02f87867389a9e660f91b64c7ca818a6b61637dc..491296a335d0ce6cd9c8f242646c3c60c762bc87 100644 (file)
--- 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 239509367e4233336806c19da964a06537d5a9b5..299795341e8a2207dc922373511e31118bbd0f8b 100644 (file)
--- 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);