[PATCH v5 02/12] xen/arm: add SVE vector length field to the domain

[Luca Fancellu <luca.fancellu@xxxxxxx>]

Add sve_vl field to arch_domain and 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 structures.

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 v4:
 - Return 0 in get_sys_vl_len() if sve is not supported, code style fix,
   removed else if since the conditions can't fallthrough, removed not
   needed condition checking for VL bits validity because it's already
   covered, so delete is_vl_valid() function. (Jan)
Changes from v3:
 - don't use fixed types when not needed, use encoded value also in
   arch_domain so rename sve_vl_bits in sve_vl. (Jan)
 - rename domainconfig_decode_vl to sve_decode_vl because it will now
   be used also to decode from arch_domain value
 - change sve_vl from uint16_t to uint8_t and move it after "type" field
   to optimize space.
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             | 12 ++++++++++++
 xen/arch/arm/domain.c                | 27 +++++++++++++++++++++++++++
 xen/arch/arm/include/asm/arm64/sve.h | 12 ++++++++++++
 xen/arch/arm/include/asm/domain.h    |  5 +++++
 xen/include/public/arch-arm.h        |  2 ++
 xen/include/public/domctl.h          |  2 +-
 6 files changed, 59 insertions(+), 1 deletion(-)

diff --git a/xen/arch/arm/arm64/sve.c b/xen/arch/arm/arm64/sve.c
index 6f3fb368c59b..78f7482619da 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 +49,14 @@ register_t vl_to_zcr(unsigned int vl)
     ASSERT(vl > 0);
     return ((vl / SVE_VL_MULTIPLE_VAL) - 1U) & ZCR_ELx_LEN_MASK;
 }
+
+/* Get the system sanitized value for VL in bits */
+unsigned int get_sys_vl_len(void)
+{
+    if ( !cpu_has_sve )
+        return 0;
+
+    /* 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..769fae8fe25e 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 = sve_decode_vl(config->arch.sve_vl);
 
     if ( (config->flags & ~flags_optional) != flags_required )
     {
@@ -602,6 +606,26 @@ 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 ( !zcr_max_bits )
+        {
+            dprintk(XENLOG_INFO, "SVE is unsupported on this machine.\n");
+            return -EINVAL;
+        }
+
+        if ( sve_vl_bits > zcr_max_bits )
+        {
+            dprintk(XENLOG_INFO,
+                    "Requested SVE vector length (%u) > supported 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 +768,9 @@ int arch_domain_create(struct domain *d,
     if ( (rc = domain_vpci_init(d)) != 0 )
         goto fail;
 
+    /* Copy the encoded vector length sve_vl from the domain configuration */
+    d->arch.sve_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 144d2b1cc485..a4c53e3e8e2e 100644
--- a/xen/arch/arm/include/asm/arm64/sve.h
+++ b/xen/arch/arm/include/asm/arm64/sve.h
@@ -13,10 +13,17 @@
 /* Vector length must be multiple of 128 */
 #define SVE_VL_MULTIPLE_VAL (128U)
 
+static inline unsigned int sve_decode_vl(unsigned int 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(unsigned int vl);
+unsigned int get_sys_vl_len(void);
 
 #else /* !CONFIG_ARM64_SVE */
 
@@ -30,6 +37,11 @@ static inline register_t vl_to_zcr(unsigned int vl)
     return 0;
 }
 
+static inline unsigned int get_sys_vl_len(void)
+{
+    return 0;
+}
+
 #endif /* CONFIG_ARM64_SVE */
 
 #endif /* _ARM_ARM64_SVE_H */
diff --git a/xen/arch/arm/include/asm/domain.h 
b/xen/arch/arm/include/asm/domain.h
index e776ee704b7d..78cc2da3d4e5 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 > 0)
+
 /*
  * Is the domain using the host memory layout?
  *
@@ -67,6 +69,9 @@ struct arch_domain
     enum domain_type type;
 #endif
 
+    /* max SVE encoded vector length */
+    uint8_t sve_vl;
+
     /* Virtual MMU */
     struct p2m_domain p2m;
 
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 529801c89ba3..e2e22cb534d6 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