From 57171b3636177d6cf3a39bec203d78e96bda4ee1 Mon Sep 17 00:00:00 2001 From: Marc Zyngier Date: Thu, 18 Mar 2021 09:43:03 +0000 Subject: [PATCH] FROMGIT: arm64: sve: Provide a conditional update accessor for ZCR_ELx 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. Acked-by: Will Deacon Signed-off-by: Marc Zyngier (cherry picked from commit 71ce1ae56e4d43a0c568e2d4bfb154cd15306a82 git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git next) Signed-off-by: Will Deacon Bug: 178098380 Test: atest VirtualizationHostTestCases on an EL2-enabled device Change-Id: I50af5ed0a57182d038f26c12a6ca9e733ac97ba4 --- 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.