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LoongArch: Save and restore CSR.CNTC for hibernation

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Save and restore CSR.CNTC for hibernation which is similar to suspend.

For host this is unnecessary because sched clock is ensured continuous,
but for kvm guest sched clock isn't enough because rdtime.d should also
be continuous.

Host::rdtime.d = Host::CSR.CNTC + counter
Guest::rdtime.d = Host::CSR.CNTC + Host::CSR.GCNTC + Guest::CSR.CNTC + counter

so,

Guest::rdtime.d = Host::rdtime.d + Host::CSR.GCNTC + Guest::CSR.CNTC

To ensure Guest::rdtime.d continuous, Host::rdtime.d should be at first
continuous, while Host::CSR.GCNTC / Guest::CSR.CNTC is maintained by KVM.

Cc: stable@vger.kernel.org
Signed-off-by: Xianglai Li <lixianglai@loongson.cn>
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: maoxiaochuan <maoxiaochuan@loongson.cn>
This commit is contained in:
Huacai Chen
2025-11-10 08:55:23 +08:00
committed by maoxiaochuan
parent bbb3085a66
commit bbe3ee2ff6
2 changed files with 4 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files
arch/loongarch/kernel/time.c
+1 -1
View File
@@ -113,7 +113,7 @@ static unsigned long __init get_loops_per_jiffy(void)
return lpj;
}
static long init_offset __nosavedata;
static long init_offset;
void save_counter(void)
{
arch/loongarch/power/hibernate.c
+3
View File
@@ -2,6 +2,7 @@
#include <asm/fpu.h>
#include <asm/loongson.h>
#include <asm/sections.h>
#include <asm/time.h>
#include <asm/tlbflush.h>
#include <linux/suspend.h>
@@ -14,6 +15,7 @@ struct pt_regs saved_regs;
void save_processor_state(void)
{
save_counter();
saved_crmd = csr_read32(LOONGARCH_CSR_CRMD);
saved_prmd = csr_read32(LOONGARCH_CSR_PRMD);
saved_euen = csr_read32(LOONGARCH_CSR_EUEN);
@@ -26,6 +28,7 @@ void save_processor_state(void)
void restore_processor_state(void)
{
sync_counter();
csr_write32(saved_crmd, LOONGARCH_CSR_CRMD);
csr_write32(saved_prmd, LOONGARCH_CSR_PRMD);
csr_write32(saved_euen, LOONGARCH_CSR_EUEN);