[PATCH v3 02/10] xen/arm: add SVE vector length field to the domain

[Luca Fancellu <luca.fancellu@xxxxxxx>]

Add sve_vl_bits field to arch_domain and sve_vl field to
xen_arch_domainconfig struct, to allow the domain to have an
information about the SVE feature and the number of SVE register
bits that are allowed for this domain.

sve_vl field is the vector length in bits divided by 128, this
allows to use less space in the xen_arch_domainconfig struct.

The field is used also to allow or forbid a domain to use SVE,
because a value equal to zero means the guest is not allowed to
use the feature.

Check that the requested vector length is lower or equal to the
platform supported vector length, otherwise fail on domain
creation.

Signed-off-by: Luca Fancellu <luca.fancellu@xxxxxxx>
---
Changes from v2:
 - rename field in xen_arch_domainconfig from "sve_vl_bits" to
   "sve_vl" and use the implicit padding after gic_version to
   store it, now this field is the VL/128. (Jan)
 - Created domainconfig_decode_vl() function to decode the sve_vl
   field and use it as plain bits value inside arch_domain.
 - Changed commit message reflecting the changes
Changes from v1:
 - no changes
Changes from RFC:
 - restore zcr_el2 in sve_restore_state, that will be introduced
   later in this serie, so remove zcr_el2 related code from this
   patch and move everything to the later patch (Julien)
 - add explicit padding into struct xen_arch_domainconfig (Julien)
 - Don't lower down the vector length, just fail to create the
   domain. (Julien)
---
 xen/arch/arm/arm64/sve.c             |  9 ++++++++
 xen/arch/arm/domain.c                | 32 ++++++++++++++++++++++++++++
 xen/arch/arm/include/asm/arm64/sve.h | 18 ++++++++++++++++
 xen/arch/arm/include/asm/domain.h    |  5 +++++
 xen/include/public/arch-arm.h        |  2 ++
 xen/include/public/domctl.h          |  2 +-
 6 files changed, 67 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/arm64/sve.c b/xen/arch/arm/arm64/sve.c
index c466de61b47f..4a4ff5dbef49 100644
--- a/xen/arch/arm/arm64/sve.c
+++ b/xen/arch/arm/arm64/sve.c
@@ -6,6 +6,7 @@
  */
 
 #include <xen/types.h>
+#include <asm/cpufeature.h>
 #include <asm/arm64/sve.h>
 #include <asm/arm64/sysregs.h>
 #include <asm/processor.h>
@@ -48,3 +49,11 @@ register_t vl_to_zcr(uint16_t vl)
     ASSERT(vl > 0);
     return ((vl / SVE_VL_MULTIPLE_VAL) - 1U) & ZCR_ELx_LEN_MASK;
 }
+
+/* Get the system sanitized value for VL in bits */
+uint16_t get_sys_vl_len(void)
+{
+    /* ZCR_ELx len field is ((len+1) * 128) = vector bits length */
+    return ((system_cpuinfo.zcr64.bits[0] & ZCR_ELx_LEN_MASK) + 1U) *
+            SVE_VL_MULTIPLE_VAL;
+}
diff --git a/xen/arch/arm/domain.c b/xen/arch/arm/domain.c
index adb6ace2e24d..470e8607fabe 100644
--- a/xen/arch/arm/domain.c
+++ b/xen/arch/arm/domain.c
@@ -13,6 +13,7 @@
 #include <xen/wait.h>
 
 #include <asm/alternative.h>
+#include <asm/arm64/sve.h>
 #include <asm/cpuerrata.h>
 #include <asm/cpufeature.h>
 #include <asm/current.h>
@@ -550,6 +551,8 @@ int arch_vcpu_create(struct vcpu *v)
     v->arch.vmpidr = MPIDR_SMP | vcpuid_to_vaffinity(v->vcpu_id);
 
     v->arch.cptr_el2 = get_default_cptr_flags();
+    if ( is_sve_domain(v->domain) )
+        v->arch.cptr_el2 &= ~HCPTR_CP(8);
 
     v->arch.hcr_el2 = get_default_hcr_flags();
 
@@ -594,6 +597,7 @@ int arch_sanitise_domain_config(struct 
xen_domctl_createdomain *config)
     unsigned int max_vcpus;
     unsigned int flags_required = (XEN_DOMCTL_CDF_hvm | XEN_DOMCTL_CDF_hap);
     unsigned int flags_optional = (XEN_DOMCTL_CDF_iommu | XEN_DOMCTL_CDF_vpmu);
+    unsigned int sve_vl_bits = domainconfig_decode_vl(config->arch.sve_vl);
 
     if ( (config->flags & ~flags_optional) != flags_required )
     {
@@ -602,6 +606,31 @@ int arch_sanitise_domain_config(struct 
xen_domctl_createdomain *config)
         return -EINVAL;
     }
 
+    /* Check feature flags */
+    if ( sve_vl_bits > 0 ) {
+        unsigned int zcr_max_bits = get_sys_vl_len();
+
+        if ( !cpu_has_sve )
+        {
+            dprintk(XENLOG_INFO, "SVE is unsupported on this machine.\n");
+            return -EINVAL;
+        }
+        else if ( !is_vl_valid(sve_vl_bits) )
+        {
+            dprintk(XENLOG_INFO, "Unsupported SVE vector length (%u)\n",
+                    sve_vl_bits);
+            return -EINVAL;
+        }
+        else if ( sve_vl_bits > zcr_max_bits )
+        {
+            dprintk(XENLOG_INFO,
+                    "The requested SVE vector length (%u) must be lower or \n"
+                    "equal to the platform supported vector length (%u)\n",
+                    sve_vl_bits, zcr_max_bits);
+            return -EINVAL;
+        }
+    }
+
     /* The P2M table must always be shared between the CPU and the IOMMU */
     if ( config->iommu_opts & XEN_DOMCTL_IOMMU_no_sharept )
     {
@@ -744,6 +773,9 @@ int arch_domain_create(struct domain *d,
     if ( (rc = domain_vpci_init(d)) != 0 )
         goto fail;
 
+    /* Copy and decode sve_vl from the domain configuration */
+    d->arch.sve_vl_bits = domainconfig_decode_vl(config->arch.sve_vl);
+
     return 0;
 
 fail:
diff --git a/xen/arch/arm/include/asm/arm64/sve.h 
b/xen/arch/arm/include/asm/arm64/sve.h
index bd56e2f24230..4b0b941c243b 100644
--- a/xen/arch/arm/include/asm/arm64/sve.h
+++ b/xen/arch/arm/include/asm/arm64/sve.h
@@ -13,10 +13,23 @@
 /* Vector length must be multiple of 128 */
 #define SVE_VL_MULTIPLE_VAL (128U)
 
+static inline bool is_vl_valid(uint16_t vl)
+{
+    /* SVE vector length is multiple of 128 and maximum 2048 */
+    return ((vl % SVE_VL_MULTIPLE_VAL) == 0) && (vl <= SVE_VL_MAX_BITS);
+}
+
+static inline uint16_t domainconfig_decode_vl(uint8_t sve_vl)
+{
+    /* SVE vector length is stored as VL/128 in xen_arch_domainconfig */
+    return sve_vl * SVE_VL_MULTIPLE_VAL;
+}
+
 #ifdef CONFIG_ARM64_SVE
 
 register_t compute_max_zcr(void);
 register_t vl_to_zcr(uint16_t vl);
+uint16_t get_sys_vl_len(void);
 
 #else /* !CONFIG_ARM64_SVE */
 
@@ -30,6 +43,11 @@ static inline register_t vl_to_zcr(uint16_t vl)
     return 0;
 }
 
+static inline uint16_t get_sys_vl_len(void)
+{
+    return 0;
+}
+
 #endif
 
 #endif /* _ARM_ARM64_SVE_H */
diff --git a/xen/arch/arm/include/asm/domain.h 
b/xen/arch/arm/include/asm/domain.h
index 42eb5df320a7..1bd669e0a5c1 100644
--- a/xen/arch/arm/include/asm/domain.h
+++ b/xen/arch/arm/include/asm/domain.h
@@ -31,6 +31,8 @@ enum domain_type {
 
 #define is_domain_direct_mapped(d) ((d)->cdf & CDF_directmap)
 
+#define is_sve_domain(d) ((d)->arch.sve_vl_bits > 0)
+
 /*
  * Is the domain using the host memory layout?
  *
@@ -114,6 +116,9 @@ struct arch_domain
     void *tee;
 #endif
 
+    /* max SVE vector length in bits */
+    uint16_t sve_vl_bits;
+
 }  __cacheline_aligned;
 
 struct arch_vcpu
diff --git a/xen/include/public/arch-arm.h b/xen/include/public/arch-arm.h
index 1528ced5097a..38311f559581 100644
--- a/xen/include/public/arch-arm.h
+++ b/xen/include/public/arch-arm.h
@@ -300,6 +300,8 @@ DEFINE_XEN_GUEST_HANDLE(vcpu_guest_context_t);
 struct xen_arch_domainconfig {
     /* IN/OUT */
     uint8_t gic_version;
+    /* IN - Contains SVE vector length divided by 128 */
+    uint8_t sve_vl;
     /* IN */
     uint16_t tee_type;
     /* IN */
diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
index 51be28c3de7c..616d7a1c070d 100644
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -21,7 +21,7 @@
 #include "hvm/save.h"
 #include "memory.h"
 
-#define XEN_DOMCTL_INTERFACE_VERSION 0x00000015
+#define XEN_DOMCTL_INTERFACE_VERSION 0x00000016
 
 /*
  * NB. xen_domctl.domain is an IN/OUT parameter for this operation.
-- 
2.34.1