A common pattern is to conditionally update ZCR_ELx in order
to avoid the "self-synchronizing" effect that writing to this
register has.
Let's provide an accessor that does exactly this.
Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
arch/arm64/include/asm/fpsimd.h | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/arch/arm64/include/asm/fpsimd.h b/arch/arm64/include/asm/fpsimd.h
index bec5f14b622a..05c9c55768b8 100644
--- a/arch/arm64/include/asm/fpsimd.h
+++ b/arch/arm64/include/asm/fpsimd.h
@@ -130,6 +130,15 @@ static inline void sve_user_enable(void)
sysreg_clear_set(cpacr_el1, 0, CPACR_EL1_ZEN_EL0EN);
}
+#define sve_cond_update_zcr_vq(val, reg) \
+ do { \
+ u64 __zcr = read_sysreg_s((reg)); \
+ u64 __new = __zcr & ~ZCR_ELx_LEN_MASK; \
+ __new |= (val) & ZCR_ELx_LEN_MASK; \
+ if (__zcr != __new) \
+ write_sysreg_s(__new, (reg)); \
+ } while (0)
+
/*
* Probing and setup functions.
* Calls to these functions must be serialised with one another.
--
2.29.2
_______________________________________________
kvmarm mailing list
kvmarm@xxxxxxxxxxxxxxxxxxxxx
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
