KVM: s390: wire up bpb feature

The new firmware interfaces for branch prediction behaviour changes
are transparently available for the guest. Nevertheless, there is
new state attached that should be migrated and properly resetted.
Provide a mechanism for handling reset, migration and VSIE.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
[Changed capability number to 152. - Radim]
Signed-off-by: Radim Krčmář <rkrcmar@redhat.com>

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index e14f381757f67b6c0111c78c491c2c1078a7f177..c1b0a9ac1dc81d2f83ba3747ebf44a0e06df260f 100644 (file)
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -207,7 +207,8 @@ struct kvm_s390_sie_block {
        __u16   ipa;                    /* 0x0056 */
        __u32   ipb;                    /* 0x0058 */
        __u32   scaoh;                  /* 0x005c */
-       __u8    reserved60;             /* 0x0060 */
+#define FPF_BPBC       0x20
+       __u8    fpf;                    /* 0x0060 */
 #define ECB_GS         0x40
 #define ECB_TE         0x10
 #define ECB_SRSI       0x04

diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
index 38535a57fef8327c3b08bf20e1f8621fd93c776a..4cdaa55fabfe2658e054b5aaf1455b6f0556e584 100644 (file)
--- a/arch/s390/include/uapi/asm/kvm.h
+++ b/arch/s390/include/uapi/asm/kvm.h
@@ -224,6 +224,7 @@ struct kvm_guest_debug_arch {
 #define KVM_SYNC_RICCB  (1UL << 7)
 #define KVM_SYNC_FPRS   (1UL << 8)
 #define KVM_SYNC_GSCB   (1UL << 9)
+#define KVM_SYNC_BPBC   (1UL << 10)
 /* length and alignment of the sdnx as a power of two */
 #define SDNXC 8
 #define SDNXL (1UL << SDNXC)
@@ -247,7 +248,9 @@ struct kvm_sync_regs {
        };
        __u8  reserved[512];    /* for future vector expansion */
        __u32 fpc;              /* valid on KVM_SYNC_VRS or KVM_SYNC_FPRS */
-       __u8 padding1[52];      /* riccb needs to be 64byte aligned */
+       __u8 bpbc : 1;          /* bp mode */
+       __u8 reserved2 : 7;
+       __u8 padding1[51];      /* riccb needs to be 64byte aligned */
        __u8 riccb[64];         /* runtime instrumentation controls block */
        __u8 padding2[192];     /* sdnx needs to be 256byte aligned */
        union {

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 2c93cbbcd15e35a389078643874bf424160f25db..2598cf243b86e08f21ccb6f9ae6ea2e28465d680 100644 (file)
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -421,6 +421,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
        case KVM_CAP_S390_GS:
                r = test_facility(133);
                break;
+       case KVM_CAP_S390_BPB:
+               r = test_facility(82);
+               break;
        default:
                r = 0;
        }
@@ -2198,6 +2201,8 @@ int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
        kvm_s390_set_prefix(vcpu, 0);
        if (test_kvm_facility(vcpu->kvm, 64))
                vcpu->run->kvm_valid_regs |= KVM_SYNC_RICCB;
+       if (test_kvm_facility(vcpu->kvm, 82))
+               vcpu->run->kvm_valid_regs |= KVM_SYNC_BPBC;
        if (test_kvm_facility(vcpu->kvm, 133))
                vcpu->run->kvm_valid_regs |= KVM_SYNC_GSCB;
        /* fprs can be synchronized via vrs, even if the guest has no vx. With
@@ -2339,6 +2344,7 @@ static void kvm_s390_vcpu_initial_reset(struct kvm_vcpu *vcpu)
        current->thread.fpu.fpc = 0;
        vcpu->arch.sie_block->gbea = 1;
        vcpu->arch.sie_block->pp = 0;
+       vcpu->arch.sie_block->fpf &= ~FPF_BPBC;
        vcpu->arch.pfault_token = KVM_S390_PFAULT_TOKEN_INVALID;
        kvm_clear_async_pf_completion_queue(vcpu);
        if (!kvm_s390_user_cpu_state_ctrl(vcpu->kvm))
@@ -3298,6 +3304,11 @@ static void sync_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
                vcpu->arch.sie_block->ecd |= ECD_HOSTREGMGMT;
                vcpu->arch.gs_enabled = 1;
        }
+       if ((kvm_run->kvm_dirty_regs & KVM_SYNC_BPBC) &&
+           test_kvm_facility(vcpu->kvm, 82)) {
+               vcpu->arch.sie_block->fpf &= ~FPF_BPBC;
+               vcpu->arch.sie_block->fpf |= kvm_run->s.regs.bpbc ? FPF_BPBC : 0;
+       }
        save_access_regs(vcpu->arch.host_acrs);
        restore_access_regs(vcpu->run->s.regs.acrs);
        /* save host (userspace) fprs/vrs */
@@ -3344,6 +3355,7 @@ static void store_regs(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
        kvm_run->s.regs.pft = vcpu->arch.pfault_token;
        kvm_run->s.regs.pfs = vcpu->arch.pfault_select;
        kvm_run->s.regs.pfc = vcpu->arch.pfault_compare;
+       kvm_run->s.regs.bpbc = (vcpu->arch.sie_block->fpf & FPF_BPBC) == FPF_BPBC;
        save_access_regs(vcpu->run->s.regs.acrs);
        restore_access_regs(vcpu->arch.host_acrs);
        /* Save guest register state */

diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index 5d6ae0326d9e8fa2707e8d066488c8313dfef879..751348348477834d874e322bd2e36b19bb2ec301 100644 (file)
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -223,6 +223,12 @@ static void unshadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
        memcpy(scb_o->gcr, scb_s->gcr, 128);
        scb_o->pp = scb_s->pp;
 
+       /* branch prediction */
+       if (test_kvm_facility(vcpu->kvm, 82)) {
+               scb_o->fpf &= ~FPF_BPBC;
+               scb_o->fpf |= scb_s->fpf & FPF_BPBC;
+       }
+
        /* interrupt intercept */
        switch (scb_s->icptcode) {
        case ICPT_PROGI:
@@ -265,6 +271,7 @@ static int shadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
        scb_s->ecb3 = 0;
        scb_s->ecd = 0;
        scb_s->fac = 0;
+       scb_s->fpf = 0;
 
        rc = prepare_cpuflags(vcpu, vsie_page);
        if (rc)
@@ -324,6 +331,9 @@ static int shadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
                        prefix_unmapped(vsie_page);
                scb_s->ecb |= scb_o->ecb & ECB_TE;
        }
+       /* branch prediction */
+       if (test_kvm_facility(vcpu->kvm, 82))
+               scb_s->fpf |= scb_o->fpf & FPF_BPBC;
        /* SIMD */
        if (test_kvm_facility(vcpu->kvm, 129)) {
                scb_s->eca |= scb_o->eca & ECA_VX;

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 7a99b98cf88e32fdb85040b0cb6973f30ffbba0b..8fb90a0819c3939eb2a74c6053c9dc5d586d9eab 100644 (file)
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -933,6 +933,7 @@ struct kvm_ppc_resize_hpt {
 #define KVM_CAP_HYPERV_VP_INDEX 149
 #define KVM_CAP_S390_AIS_MIGRATION 150
 #define KVM_CAP_PPC_GET_CPU_CHAR 151
+#define KVM_CAP_S390_BPB 152
 
 #ifdef KVM_CAP_IRQ_ROUTING