Patch "riscv: Save/restore envcfg CSR during CPU suspend" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    riscv: Save/restore envcfg CSR during CPU suspend

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     riscv-save-restore-envcfg-csr-during-cpu-suspend.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 9a04caaf4634af3b91878501d2ff49d8b6823c82
Author: Samuel Holland <samuel.holland@xxxxxxxxxx>
Date:   Tue Feb 27 22:55:35 2024 -0800

    riscv: Save/restore envcfg CSR during CPU suspend
    
    [ Upstream commit 05ab803d1ad8ac505ade77c6bd3f86b1b4ea0dc4 ]
    
    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@xxxxxxxxxxxxxxx> # v6.7+
    Fixes: 43c16d51a19b ("RISC-V: Enable cbo.zero in usermode")
    Signed-off-by: Samuel Holland <samuel.holland@xxxxxxxxxx>
    Reviewed-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx>
    Reviewed-by: Andrew Jones <ajones@xxxxxxxxxxxxxxxx>
    Link: https://lore.kernel.org/r/20240228065559.3434837-4-samuel.holland@xxxxxxxxxx
    Signed-off-by: Palmer Dabbelt <palmer@xxxxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/riscv/include/asm/suspend.h b/arch/riscv/include/asm/suspend.h
index 02f87867389a9..491296a335d0c 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 3c89b8ec69c49..91957e0a5494f 100644
--- a/arch/riscv/kernel/suspend.c
+++ b/arch/riscv/kernel/suspend.c
@@ -11,6 +11,8 @@
 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);
 
@@ -32,6 +34,8 @@ 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);