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@xxxxxxxxxx>
---
v1->v2: - review feedback from David
- rename seb(c) into bpb(c)
arch/s390/include/asm/kvm_host.h | 3 ++-
arch/s390/include/uapi/asm/kvm.h | 5 ++++-
arch/s390/kvm/kvm-s390.c | 12 ++++++++++++
arch/s390/kvm/vsie.c | 10 ++++++++++
include/uapi/linux/kvm.h | 1 +
5 files changed, 29 insertions(+), 2 deletions(-)
diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index e14f381..c1b0a9a 100644
--- 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 38535a57..4cdaa55 100644
--- 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 2c93cbb..2598cf243 100644
--- 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 5d6ae03..7513483 100644
--- 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 496e59a..79f6050 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -932,6 +932,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_HYPERV_SYNIC2 148
#define KVM_CAP_HYPERV_VP_INDEX 149
#define KVM_CAP_S390_AIS_MIGRATION 150
+#define KVM_CAP_S390_BPB 151
#ifdef KVM_CAP_IRQ_ROUTING
--
2.9.4
--
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