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FROMGIT: arm64: sve: Provide a conditional update accessor for ZCR_ELx

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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 <will@kernel.org>
Signed-off-by: Marc Zyngier <maz@kernel.org>
(cherry picked from commit 71ce1ae56e4d43a0c568e2d4bfb154cd15306a82
 git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git next)
Signed-off-by: Will Deacon <willdeacon@google.com>
Bug: 178098380
Test: atest VirtualizationHostTestCases on an EL2-enabled device
Change-Id: I50af5ed0a57182d038f26c12a6ca9e733ac97ba4
This commit is contained in:
Marc Zyngier
2021-03-18 09:43:03 +00:00
committed by Quentin Perret
parent ac5f5708bb
commit 57171b3636
1 changed files with 9 additions and 0 deletions
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9
arch/arm64/include/asm/fpsimd.h
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@@ -130,6 +130,15 @@ static inline void sve_user_enable(void)
sysreg_clear_set(cpacr_el1, 0, CPACR_EL1_ZEN_EL0EN); 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. * Probing and setup functions.
* Calls to these functions must be serialised with one another. * Calls to these functions must be serialised with one another.