KVM: arm64: Factor out core register ID enumeration

In preparation for adding logic to filter out some KVM_REG_ARM_CORE
registers from the KVM_GET_REG_LIST output, this patch factors out
the core register enumeration into a separate function and rebuilds
num_core_regs() on top of it.

This may be a little more expensive (depending on how good a job
the compiler does of specialising the code), but KVM_GET_REG_LIST
is not a hot path.

This will make it easier to consolidate ID filtering code in one
place.

No functional change.

Signed-off-by: Dave Martin <Dave.Martin@arm.com>
Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Tested-by: zhang.lei <zhang.lei@jp.fujitsu.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

diff --git a/arch/arm64/kvm/guest.c b/arch/arm64/kvm/guest.c
index 3e38eb28b03cceed699fb6ce55cbb373d4eb9882..a391a61b1033c38ac6dbb731d802788ea36a5f6f 100644 (file)
--- a/arch/arm64/kvm/guest.c
+++ b/arch/arm64/kvm/guest.c
@@ -23,6 +23,7 @@
 #include <linux/err.h>
 #include <linux/kvm_host.h>
 #include <linux/module.h>
+#include <linux/stddef.h>
 #include <linux/string.h>
 #include <linux/vmalloc.h>
 #include <linux/fs.h>
@@ -194,9 +195,28 @@ int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
        return -EINVAL;
 }
 
+static int kvm_arm_copy_core_reg_indices(u64 __user *uindices)
+{
+       unsigned int i;
+       int n = 0;
+       const u64 core_reg = KVM_REG_ARM64 | KVM_REG_SIZE_U64 | KVM_REG_ARM_CORE;
+
+       for (i = 0; i < sizeof(struct kvm_regs) / sizeof(__u32); i++) {
+               if (uindices) {
+                       if (put_user(core_reg | i, uindices))
+                               return -EFAULT;
+                       uindices++;
+               }
+
+               n++;
+       }
+
+       return n;
+}
+
 static unsigned long num_core_regs(void)
 {
-       return sizeof(struct kvm_regs) / sizeof(__u32);
+       return kvm_arm_copy_core_reg_indices(NULL);
 }
 
 /**
@@ -276,15 +296,12 @@ unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu)
  */
 int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
 {
-       unsigned int i;
-       const u64 core_reg = KVM_REG_ARM64 | KVM_REG_SIZE_U64 | KVM_REG_ARM_CORE;
        int ret;
 
-       for (i = 0; i < sizeof(struct kvm_regs) / sizeof(__u32); i++) {
-               if (put_user(core_reg | i, uindices))
-                       return -EFAULT;
-               uindices++;
-       }
+       ret = kvm_arm_copy_core_reg_indices(uindices);
+       if (ret)
+               return ret;
+       uindices += ret;
 
        ret = kvm_arm_copy_fw_reg_indices(vcpu, uindices);
        if (ret)