KVM: s390: sync of fp registers via kvm_run

As we already store the floating point registers in the vector save area
in floating point register format when we don't have MACHINE_HAS_VX, we can
directly expose them to user space using a new sync flag.

The floating point registers will be valid when KVM_SYNC_FPRS is set. The
fpc will also be valid when KVM_SYNC_FPRS is set.

Either KVM_SYNC_FPRS or KVM_SYNC_VRS will be enabled, never both.

Let's also change two positions where we access vrs, making the code easier
to read and one comment superfluous.

Suggested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

1 files changed, 6 insertions, 2 deletions

diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
index fe84bd5fe7ce..347fe5afa419 100644
--- a/arch/s390/include/uapi/asm/kvm.h
+++ b/arch/s390/include/uapi/asm/kvm.h
@@ -154,6 +154,7 @@ struct kvm_guest_debug_arch {
 #define KVM_SYNC_PFAULT (1UL << 5)
 #define KVM_SYNC_VRS    (1UL << 6)
 #define KVM_SYNC_RICCB  (1UL << 7)
+#define KVM_SYNC_FPRS   (1UL << 8)
 /* definition of registers in kvm_run */
 struct kvm_sync_regs {
         __u64 prefix;   /* prefix register */
@@ -168,9 +169,12 @@ struct kvm_sync_regs {
         __u64 pft;      /* pfault token [PFAULT] */
         __u64 pfs;      /* pfault select [PFAULT] */
         __u64 pfc;      /* pfault compare [PFAULT] */
-        __u64 vrs[32][2];       /* vector registers */
+        union {
+                __u64 vrs[32][2];       /* vector registers (KVM_SYNC_VRS) */
+                __u64 fprs[16];         /* fp registers (KVM_SYNC_FPRS) */
+        };
         __u8  reserved[512];    /* for future vector expansion */
-        __u32 fpc;      /* only valid with vector registers */
+        __u32 fpc;              /* valid on KVM_SYNC_VRS or KVM_SYNC_FPRS */
         __u8 padding[52];       /* riccb needs to be 64byte aligned */
         __u8 riccb[64];         /* runtime instrumentation controls block */
 };