KVM: ARM: User space API for getting/setting co-proc registers

The following three ioctls are implemented:
 -  KVM_GET_REG_LIST
 -  KVM_GET_ONE_REG
 -  KVM_SET_ONE_REG

Now we have a table for all the cp15 registers, we can drive a generic
API.

The register IDs carry the following encoding:

ARM registers are mapped using the lower 32 bits.  The upper 16 of that
is the register group type, or coprocessor number:

ARM 32-bit CP15 registers have the following id bit patterns:
  0x4002 0000 000F <zero:1> <crn:4> <crm:4> <opc1:4> <opc2:3>

ARM 64-bit CP15 registers have the following id bit patterns:
  0x4003 0000 000F <zero:1> <zero:4> <crm:4> <opc1:4> <zero:3>

For futureproofing, we need to tell QEMU about the CP15 registers the
host lets the guest access.

It will need this information to restore a current guest on a future
CPU or perhaps a future KVM which allow some of these to be changed.

We use a separate table for these, as they're only for the userspace API.
Reviewed-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Christoffer Dall <c.dall@virtualopensystems.com>

Documentation/virtual/kvm/api.txt

@@ -1799,6 +1799,11 @@ is the register group type, or coprocessor number:
 ARM core registers have the following id bit patterns:
   0x4002 0000 0010 <index into the kvm_regs struct:16>
 
+ARM 32-bit CP15 registers have the following id bit patterns:
+  0x4002 0000 000F <zero:1> <crn:4> <crm:4> <opc1:4> <opc2:3>
+
+ARM 64-bit CP15 registers have the following id bit patterns:
+  0x4003 0000 000F <zero:1> <zero:4> <crm:4> <opc1:4> <zero:3>
 
 
 4.69 KVM_GET_ONE_REG

arch/arm/include/asm/kvm_coproc.h

@@ -34,5 +34,14 @@ int kvm_handle_cp14_load_store(struct kvm_vcpu *vcpu, struct kvm_run *run);
 int kvm_handle_cp14_access(struct kvm_vcpu *vcpu, struct kvm_run *run);
 int kvm_handle_cp15_32(struct kvm_vcpu *vcpu, struct kvm_run *run);
 int kvm_handle_cp15_64(struct kvm_vcpu *vcpu, struct kvm_run *run);
+
+unsigned long kvm_arm_num_guest_msrs(struct kvm_vcpu *vcpu);
+int kvm_arm_copy_msrindices(struct kvm_vcpu *vcpu, u64 __user *uindices);
 void kvm_coproc_table_init(void);
+
+struct kvm_one_reg;
+int kvm_arm_copy_coproc_indices(struct kvm_vcpu *vcpu, u64 __user *uindices);
+int kvm_arm_coproc_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *);
+int kvm_arm_coproc_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *);
+unsigned long kvm_arm_num_coproc_regs(struct kvm_vcpu *vcpu);
 #endif /* __ARM_KVM_COPROC_H__ */

arch/arm/include/asm/kvm_host.h

@@ -27,6 +27,7 @@
 #define KVM_MEMORY_SLOTS 32
 #define KVM_PRIVATE_MEM_SLOTS 4
 #define KVM_COALESCED_MMIO_PAGE_OFFSET 1
+#define KVM_HAVE_ONE_REG
 
 #define KVM_VCPU_MAX_FEATURES 0
 
@@ -137,6 +138,9 @@ int kvm_unmap_hva_range(struct kvm *kvm,
 			unsigned long start, unsigned long end);
 void kvm_set_spte_hva(struct kvm *kvm, unsigned long hva, pte_t pte);
 
+unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu);
+int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *indices);
+
 /* We do not have shadow page tables, hence the empty hooks */
 static inline int kvm_age_hva(struct kvm *kvm, unsigned long hva)
 {

arch/arm/kvm/guest.c

@@ -26,6 +26,7 @@
 #include <asm/kvm.h>
 #include <asm/kvm_asm.h>
 #include <asm/kvm_emulate.h>
+#include <asm/kvm_coproc.h>
 
 #define VM_STAT(x) { #x, offsetof(struct kvm, stat.x), KVM_STAT_VM }
 #define VCPU_STAT(x) { #x, offsetof(struct kvm_vcpu, stat.x), KVM_STAT_VCPU }
@@ -119,7 +120,7 @@ static unsigned long num_core_regs(void)
  */
 unsigned long kvm_arm_num_regs(struct kvm_vcpu *vcpu)
 {
-	return num_core_regs();
+	return num_core_regs() + kvm_arm_num_coproc_regs(vcpu);
 }
 
 /**
@@ -138,7 +139,7 @@ int kvm_arm_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
 		uindices++;
 	}
 
-	return 0;
+	return kvm_arm_copy_coproc_indices(vcpu, uindices);
 }
 
 int kvm_arm_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
@@ -151,7 +152,7 @@ int kvm_arm_get_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 	if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_CORE)
 		return get_core_reg(vcpu, reg);
 
-	return -EINVAL;
+	return kvm_arm_coproc_get_reg(vcpu, reg);
 }
 
 int kvm_arm_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
@@ -164,7 +165,7 @@ int kvm_arm_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg)
 	if ((reg->id & KVM_REG_ARM_COPROC_MASK) == KVM_REG_ARM_CORE)
 		return set_core_reg(vcpu, reg);
 
-	return -EINVAL;
+	return kvm_arm_coproc_set_reg(vcpu, reg);
 }
 
 int kvm_arch_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu,