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>

diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
index fe84bd5..347fe5a 100644 (file)
--- 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 */
 };

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 8fcdf98..2270fe4 100644 (file)
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -1419,6 +1419,8 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
         */
        if (MACHINE_HAS_VX)
                vcpu->run->kvm_valid_regs |= KVM_SYNC_VRS;
+       else
+               vcpu->run->kvm_valid_regs |= KVM_SYNC_FPRS;
 
        if (kvm_is_ucontrol(vcpu->kvm))
                return __kvm_ucontrol_vcpu_init(vcpu);
@@ -1433,10 +1435,10 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
        vcpu->arch.host_fpregs.fpc = current->thread.fpu.fpc;
        vcpu->arch.host_fpregs.regs = current->thread.fpu.regs;
 
-       /* Depending on MACHINE_HAS_VX, data stored to vrs either
-        * has vector register or floating point register format.
-        */
-       current->thread.fpu.regs = vcpu->run->s.regs.vrs;
+       if (MACHINE_HAS_VX)
+               current->thread.fpu.regs = vcpu->run->s.regs.vrs;
+       else
+               current->thread.fpu.regs = vcpu->run->s.regs.fprs;
        current->thread.fpu.fpc = vcpu->run->s.regs.fpc;
        if (test_fp_ctl(current->thread.fpu.fpc))
                /* User space provided an invalid FPC, let's clear it */
@@ -2389,7 +2391,7 @@ int kvm_s390_store_status_unloaded(struct kvm_vcpu *vcpu, unsigned long gpa)
                                     fprs, 128);
        } else {
                rc = write_guest_abs(vcpu, gpa + __LC_FPREGS_SAVE_AREA,
-                                    vcpu->run->s.regs.vrs, 128);
+                                    vcpu->run->s.regs.fprs, 128);
        }
        rc |= write_guest_abs(vcpu, gpa + __LC_GPREGS_SAVE_AREA,
                              vcpu->run->s.regs.gprs, 128);