[PATCH 6.6 258/299] arm64/sme: Restore SME registers on exit from suspend

Greg Kroah-Hartman
2024-02-27T13:58:53Z

From: Mark Brown <broonie@kernel.org>

[ Upstream commit 9533864816fb4a6207c63b7a98396351ce1a9fae ]

The fields in SMCR_EL1 and SMPRI_EL1 reset to an architecturally UNKNOWN
value. Since we do not otherwise manage the traps configured in this
register at runtime we need to reconfigure them after a suspend in case
nothing else was kind enough to preserve them for us.

The vector length will be restored as part of restoring the SME state for
the next SME using task.

Fixes: a1f4ccd25cc2 ("arm64/sme: Provide Kconfig for SME")
Reported-by: Jackson Cooper-Driver <Jackson.Cooper-Driver@arm.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20240213-arm64-sme-resume-v3-1-17e05e493471@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm64/include/asm/fpsimd.h | 2 ++
arch/arm64/kernel/fpsimd.c | 14 ++++++++++++++
arch/arm64/kernel/suspend.c | 3 +++
3 files changed, 19 insertions(+)

diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h
index 8df46f186c64b..b54506d707380 100644
--- a/arch/arm64/include/asm/fpsimd.h
+++ b/arch/arm64/include/asm/fpsimd.h
@@ -360,6 +360,7 @@ extern void sme_alloc(struct task_struct *task, bool flush);
extern unsigned int sme_get_vl(void);
extern int sme_set_current_vl(unsigned long arg);
extern int sme_get_current_vl(void);
+extern void sme_suspend_exit(void);

/*
* Return how many bytes of memory are required to store the full SME
@@ -395,6 +396,7 @@ static inline int sme_max_vl(void) { return 0; }
static inline int sme_max_virtualisable_vl(void) { return 0; }
static inline int sme_set_current_vl(unsigned long arg) { return -EINVAL; }
static inline int sme_get_current_vl(void) { return -EINVAL; }
+static inline void sme_suspend_exit(void) { }

static inline size_t sme_state_size(struct task_struct const *task)
{
diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 1e1e0511c0081..ce0bc01b4208d 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -1406,6 +1406,20 @@ void __init sme_setup(void)
get_sme_default_vl());
}

+void sme_suspend_exit(void)
+{
+ u64 smcr = 0;
+
+ if (!system_supports_sme())
+ return;
+
+ if (system_supports_fa64())
+ smcr |= SMCR_ELx_FA64;
+
+ write_sysreg_s(smcr, SYS_SMCR_EL1);
+ write_sysreg_s(0, SYS_SMPRI_EL1);
+}
+
#endif /* CONFIG_ARM64_SME */

static void sve_init_regs(void)
diff --git a/arch/arm64/kernel/suspend.c b/arch/arm64/kernel/suspend.c
index 0fbdf5fe64d8d..045af2bfd656a 100644
--- a/arch/arm64/kernel/suspend.c
+++ b/arch/arm64/kernel/suspend.c
@@ -12,6 +12,7 @@
#include <asm/daifflags.h>
#include <asm/debug-monitors.h>
#include <asm/exec.h>
+#include <asm/fpsimd.h>
#include <asm/mte.h>
#include <asm/memory.h>
#include <asm/mmu_context.h>
@@ -80,6 +81,8 @@ void notrace __cpu_suspend_exit(void)
*/
spectre_v4_enable_mitigation(NULL);

+ sme_suspend_exit();
+
/* Restore additional feature-specific configuration */
ptrauth_suspend_exit();
}
--
2.43.0