Add a command line parameter to allow Dom0 the use of SVE resources,
the command line parameter sve=<integer>, sub argument of dom0=,
controls the feature on this domain and sets the maximum SVE vector
length for Dom0.
Add a new function, parse_signed_integer(), to parse an integer
command line argument.
Signed-off-by: Luca Fancellu <luca.fance...@arm.com>
---
Changes from v4:
- Negative values as user param means max supported HW VL (Jan)
- update documentation, make use of no_config_param(), rename
parse_integer into parse_signed_integer and take long long *,
also put a comment on the -2 return condition, update
declaration comment to reflect the modifications (Jan)
Changes from v3:
- Don't use fixed len types when not needed (Jan)
- renamed domainconfig_encode_vl to sve_encode_vl
- Use a sub argument of dom0= to enable the feature (Jan)
- Add parse_integer() function
Changes from v2:
- xen_domctl_createdomain field has changed into sve_vl and its
value now is the VL / 128, create an helper function for that.
Changes from v1:
- No changes
Changes from RFC:
- Changed docs to explain that the domain won't be created if the
requested vector length is above the supported one from the
platform.
---
docs/misc/xen-command-line.pandoc | 18 ++++++++++++++++--
xen/arch/arm/arm64/sve.c | 21 +++++++++++++++++++++
xen/arch/arm/domain_build.c | 27 +++++++++++++++++++++++++++
xen/arch/arm/include/asm/arm64/sve.h | 15 +++++++++++++++
xen/common/kernel.c | 25 +++++++++++++++++++++++++
xen/include/xen/lib.h | 10 ++++++++++
6 files changed, 114 insertions(+), 2 deletions(-)
diff --git a/docs/misc/xen-command-line.pandoc
b/docs/misc/xen-command-line.pandoc
index e0b89b7d3319..9c0790ce6c7c 100644
--- a/docs/misc/xen-command-line.pandoc
+++ b/docs/misc/xen-command-line.pandoc
@@ -777,9 +777,9 @@ Specify the bit width of the DMA heap.
### dom0
= List of [ pv | pvh, shadow=<bool>, verbose=<bool>,
- cpuid-faulting=<bool>, msr-relaxed=<bool> ]
+ cpuid-faulting=<bool>, msr-relaxed=<bool> ] (x86)
- Applicability: x86
+ = List of [ sve=<integer> ] (Arm)
Controls for how dom0 is constructed on x86 systems.
@@ -838,6 +838,20 @@ Controls for how dom0 is constructed on x86 systems.
If using this option is necessary to fix an issue, please report a bug.
+Enables features on dom0 on Arm systems.
+
+* The `sve` integer parameter enables Arm SVE usage for Dom0 domain and sets
+ the maximum SVE vector length.
+ A value equal to 0 disables the feature, this is the default value.
+ Values below 0 means the feature uses the maximum SVE vector length
+ supported by hardware, please be aware that if the hardware doesn't
supports
+ SVE, the feature remains disabled.
+ Values above 0 explicitly set the maximum SVE vector length for Dom0,
+ allowed values are from 128 to maximum 2048, being multiple of 128.
+ Please note that when the user explicitly specify the value, if that value
+ is above the hardware supported maximum SVE vector length, the domain
+ creation will fail and the system will stop.
+
### dom0-cpuid
= List of comma separated booleans
diff --git a/xen/arch/arm/arm64/sve.c b/xen/arch/arm/arm64/sve.c
index 5485648850a0..ad5db62e1805 100644
--- a/xen/arch/arm/arm64/sve.c
+++ b/xen/arch/arm/arm64/sve.c
@@ -9,6 +9,9 @@
#include <xen/sizes.h>
#include <asm/arm64/sve.h>
+/* opt_dom0_sve: allow Dom0 to use SVE and set maximum vector length. */
+int __initdata opt_dom0_sve;
+
extern unsigned int sve_get_hw_vl(void);
extern void sve_save_ctx(uint64_t *sve_ctx, uint64_t *pregs, int save_ffr);
extern void sve_load_ctx(uint64_t const *sve_ctx, uint64_t const *pregs,
@@ -118,3 +121,21 @@ void sve_restore_state(struct vcpu *v)
sve_load_ctx(sve_ctx_zreg_end, v->arch.vfp.fpregs, 1);
}
+
+int __init sve_sanitize_vl_param(int val, unsigned int *out)
+{
+ /*
+ * Negative SVE parameter value means to use the maximum supported
+ * vector length, otherwise if a positive value is provided, check if the
+ * vector length is a multiple of 128 and not bigger than the maximum value
+ * 2048
+ */
+ if ( val < 0 )
+ *out = get_sys_vl_len();
+ else if ( ((val % SVE_VL_MULTIPLE_VAL) == 0) && (val <= SVE_VL_MAX_BITS) )
+ *out = val;
+ else
+ return -1;
+
+ return 0;
+}
diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index eeb4662f0eee..3f30ef5c37b6 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -26,6 +26,7 @@
#include <asm/platform.h>
#include <asm/psci.h>
#include <asm/setup.h>
+#include <asm/arm64/sve.h>
#include <asm/cpufeature.h>
#include <asm/domain_build.h>
#include <xen/event.h>
@@ -61,6 +62,21 @@ custom_param("dom0_mem", parse_dom0_mem);
int __init parse_arch_dom0_param(const char *s, const char *e)
{
+ long long val;
+
+ if ( !parse_signed_integer("sve", s, e, &val) )
+ {
+#ifdef CONFIG_ARM64_SVE
+ if ( (val >= INT_MIN) && (val <= INT_MAX) )
+ opt_dom0_sve = val;
+ else
+ printk(XENLOG_INFO "'sve=%lld' value out of range!\n", val);
+#else
+ no_config_param("ARM64_SVE", "sve", s, e);
+#endif
+ return 0;
+ }
+
return -EINVAL;
}
@@ -4109,6 +4125,17 @@ void __init create_dom0(void)
if ( iommu_enabled )
dom0_cfg.flags |= XEN_DOMCTL_CDF_iommu;
+ if ( opt_dom0_sve )
+ {
+ unsigned int vl;
+
+ if ( !sve_sanitize_vl_param(opt_dom0_sve, &vl) )
+ dom0_cfg.arch.sve_vl = sve_encode_vl(vl);
+ else
+ printk(XENLOG_WARNING
+ "SVE vector length error, disable feature for Dom0\n");
+ }
+
dom0 = domain_create(0, &dom0_cfg, CDF_privileged | CDF_directmap);
if ( IS_ERR(dom0) )
panic("Error creating domain 0 (rc = %ld)\n", PTR_ERR(dom0));
diff --git a/xen/arch/arm/include/asm/arm64/sve.h
b/xen/arch/arm/include/asm/arm64/sve.h
index fc162c9d2cf7..f1801876b5de 100644
--- a/xen/arch/arm/include/asm/arm64/sve.h
+++ b/xen/arch/arm/include/asm/arm64/sve.h
@@ -19,8 +19,15 @@ static inline unsigned int sve_decode_vl(unsigned int sve_vl)
return sve_vl * SVE_VL_MULTIPLE_VAL;
}
+static inline unsigned int sve_encode_vl(unsigned int sve_vl_bits)
+{
+ return sve_vl_bits / SVE_VL_MULTIPLE_VAL;
+}
+
#ifdef CONFIG_ARM64_SVE
+extern int opt_dom0_sve;
+
register_t compute_max_zcr(void);
register_t vl_to_zcr(unsigned int vl);
unsigned int get_sys_vl_len(void);
@@ -28,9 +35,12 @@ int sve_context_init(struct vcpu *v);
void sve_context_free(struct vcpu *v);
void sve_save_state(struct vcpu *v);
void sve_restore_state(struct vcpu *v);
+int sve_sanitize_vl_param(int val, unsigned int *out);
#else /* !CONFIG_ARM64_SVE */
+#define opt_dom0_sve (0)
+
static inline register_t compute_max_zcr(void)
{
return 0;
@@ -55,6 +65,11 @@ static inline void sve_context_free(struct vcpu *v) {}
static inline void sve_save_state(struct vcpu *v) {}
static inline void sve_restore_state(struct vcpu *v) {}
+static inline int sve_sanitize_vl_param(int val, unsigned int *out)
+{
+ return -1;
+}
+
#endif /* CONFIG_ARM64_SVE */
#endif /* _ARM_ARM64_SVE_H */
diff --git a/xen/common/kernel.c b/xen/common/kernel.c
index f7b1f65f373c..29d05282c8bb 100644
--- a/xen/common/kernel.c
+++ b/xen/common/kernel.c
@@ -314,6 +314,31 @@ int parse_boolean(const char *name, const char *s, const
char *e)
return -1;
}
+int __init parse_signed_integer(const char *name, const char *s, const char *e,
+ long long *val)
+{
+ size_t slen, nlen;
+ const char *str;
+ long long pval;
+
+ slen = e ? ({ ASSERT(e >= s); e - s; }) : strlen(s);
+ nlen = strlen(name);
+
+ /* Does s start with name or contains only the name? */
+ if ( (slen <= nlen) || strncmp(s, name, nlen) || (s[nlen] != '=') )
+ return -1;
+
+ pval = simple_strtoll(&s[nlen + 1], &str, 0);
+
+ /* Number not recognised */
+ if ( str != e )
+ return -2;
+
+ *val = pval;
+
+ return 0;
+}
+
int cmdline_strcmp(const char *frag, const char *name)
{
for ( ; ; frag++, name++ )
diff --git a/xen/include/xen/lib.h b/xen/include/xen/lib.h
index e914ccade095..5343ee7a944a 100644
--- a/xen/include/xen/lib.h
+++ b/xen/include/xen/lib.h
@@ -94,6 +94,16 @@ int parse_bool(const char *s, const char *e);
*/
int parse_boolean(const char *name, const char *s, const char *e);
+/**
+ * Given a specific name, parses a string of the form:
+ * $NAME=<integer number>
+ * returning 0 and a value in val, for a recognised integer.
+ * Returns -1 for name not found, general errors, or -2 if name is found but
+ * not recognised number.
+ */
+int parse_signed_integer(const char *name, const char *s, const char *e,
+ long long *val);
+
/**
* Very similar to strcmp(), but will declare a match if the NUL in 'name'
* lines up with comma, colon, semicolon or equals in 'frag'. Designed for
--
2.34.1
