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arm64/sve: In-kernel vector length availability query interface

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KVM will need to interrogate the set of SVE vector lengths
available on the system.

This patch exposes the relevant bits to the kernel, along with a
sve_vq_available() helper to check whether a particular vector
length is supported.

__vq_to_bit() and __bit_to_vq() are not intended for use outside
these functions: now that these are exposed outside fpsimd.c, they
are prefixed with __ in order to provide an extra hint that they
are not intended for general-purpose use.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: zhang.lei <zhang.lei@jp.fujitsu.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Dave Martin
2018-09-28 14:39:21 +01:00
committed by Marc Zyngier
parent 8e3c54c8b6
commit ead9e430c0
2 changed files with 37 additions and 27 deletions
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29
arch/arm64/include/asm/fpsimd.h
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@@ -24,10 +24,13 @@
#ifndef __ASSEMBLY__
#include <linux/bitmap.h>
#include <linux/build_bug.h>
#include <linux/bug.h>
#include <linux/cache.h>
#include <linux/init.h>
#include <linux/stddef.h>
#include <linux/types.h>
#if defined(__KERNEL__) && defined(CONFIG_COMPAT)
/* Masks for extracting the FPSR and FPCR from the FPSCR */
@@ -89,6 +92,32 @@ extern u64 read_zcr_features(void);
extern int __ro_after_init sve_max_vl;
extern int __ro_after_init sve_max_virtualisable_vl;
/* Set of available vector lengths, as vq_to_bit(vq): */
extern __ro_after_init DECLARE_BITMAP(sve_vq_map, SVE_VQ_MAX);
/*
* Helpers to translate bit indices in sve_vq_map to VQ values (and
* vice versa). This allows find_next_bit() to be used to find the
* _maximum_ VQ not exceeding a certain value.
*/
static inline unsigned int __vq_to_bit(unsigned int vq)
{
return SVE_VQ_MAX - vq;
}
static inline unsigned int __bit_to_vq(unsigned int bit)
{
if (WARN_ON(bit >= SVE_VQ_MAX))
bit = SVE_VQ_MAX - 1;
return SVE_VQ_MAX - bit;
}
/* Ensure vq >= SVE_VQ_MIN && vq <= SVE_VQ_MAX before calling this function */
static inline bool sve_vq_available(unsigned int vq)
{
return test_bit(__vq_to_bit(vq), sve_vq_map);
}
#ifdef CONFIG_ARM64_SVE