[PATCH v9 2/2] s390/kvm: diagnose 0x318 sync and reset

Collin Walling
2020-06-22T15:46:57Z

DIAGNOSE 0x318 (diag318) sets information regarding the environment
the VM is running in (Linux, z/VM, etc) and is observed via
firmware/service events.

This is a privileged s390x instruction that must be intercepted by
SIE. Userspace handles the instruction as well as migration. Data
is communicated via VCPU register synchronization.

The Control Program Name Code (CPNC) is stored in the SIE block. The
CPNC along with the Control Program Version Code (CPVC) are stored
in the kvm_vcpu_arch struct.

This data is reset on load normal and clear resets.

Signed-off-by: Collin Walling <walling@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
---
arch/s390/include/asm/kvm_host.h | 4 +++-
arch/s390/include/uapi/asm/kvm.h | 5 ++++-
arch/s390/kvm/kvm-s390.c | 11 ++++++++++-
arch/s390/kvm/vsie.c | 1 +
include/uapi/linux/kvm.h | 1 +
5 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 3d554887794e..8bdf6f1607ca 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -260,7 +260,8 @@ struct kvm_s390_sie_block {
__u32 scaol; /* 0x0064 */
__u8 sdf; /* 0x0068 */
__u8 epdx; /* 0x0069 */
- __u8 reserved6a[2]; /* 0x006a */
+ __u8 cpnc; /* 0x006a */
+ __u8 reserved6b; /* 0x006b */
__u32 todpr; /* 0x006c */
#define GISA_FORMAT1 0x00000001
__u32 gd; /* 0x0070 */
@@ -745,6 +746,7 @@ struct kvm_vcpu_arch {
bool gs_enabled;
bool skey_enabled;
struct kvm_s390_pv_vcpu pv;
+ union diag318_info diag318_info;
};

struct kvm_vm_stat {
diff --git a/arch/s390/include/uapi/asm/kvm.h b/arch/s390/include/uapi/asm/kvm.h
index 436ec7636927..2ae1b660086c 100644
--- a/arch/s390/include/uapi/asm/kvm.h
+++ b/arch/s390/include/uapi/asm/kvm.h
@@ -231,11 +231,13 @@ struct kvm_guest_debug_arch {
#define KVM_SYNC_GSCB (1UL << 9)
#define KVM_SYNC_BPBC (1UL << 10)
#define KVM_SYNC_ETOKEN (1UL << 11)
+#define KVM_SYNC_DIAG318 (1UL << 12)

#define KVM_SYNC_S390_VALID_FIELDS \
(KVM_SYNC_PREFIX | KVM_SYNC_GPRS | KVM_SYNC_ACRS | KVM_SYNC_CRS | \
KVM_SYNC_ARCH0 | KVM_SYNC_PFAULT | KVM_SYNC_VRS | KVM_SYNC_RICCB | \
- KVM_SYNC_FPRS | KVM_SYNC_GSCB | KVM_SYNC_BPBC | KVM_SYNC_ETOKEN)
+ KVM_SYNC_FPRS | KVM_SYNC_GSCB | KVM_SYNC_BPBC | KVM_SYNC_ETOKEN | \
+ KVM_SYNC_DIAG318)

/* length and alignment of the sdnx as a power of two */
#define SDNXC 8
@@ -254,6 +256,7 @@ struct kvm_sync_regs {
__u64 pft; /* pfault token [PFAULT] */
__u64 pfs; /* pfault select [PFAULT] */
__u64 pfc; /* pfault compare [PFAULT] */
+ __u64 diag318; /* diagnose 0x318 info */
union {
__u64 vrs[32][2]; /* vector registers (KVM_SYNC_VRS) */
__u64 fprs[16]; /* fp registers (KVM_SYNC_FPRS) */
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index d0ff26d157bc..b05ad718b64b 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -545,6 +545,7 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_S390_AIS_MIGRATION:
case KVM_CAP_S390_VCPU_RESETS:
case KVM_CAP_SET_GUEST_DEBUG:
+ case KVM_CAP_S390_DIAG318:
r = 1;
break;
case KVM_CAP_S390_HPAGE_1M:
@@ -3267,7 +3268,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
KVM_SYNC_ACRS |
KVM_SYNC_CRS |
KVM_SYNC_ARCH0 |
- KVM_SYNC_PFAULT;
+ KVM_SYNC_PFAULT |
+ KVM_SYNC_DIAG318;
kvm_s390_set_prefix(vcpu, 0);
if (test_kvm_facility(vcpu->kvm, 64))
vcpu->run->kvm_valid_regs |= KVM_SYNC_RICCB;
@@ -3562,6 +3564,7 @@ static void kvm_arch_vcpu_ioctl_initial_reset(struct kvm_vcpu *vcpu)
vcpu->arch.sie_block->pp = 0;
vcpu->arch.sie_block->fpf &= ~FPF_BPBC;
vcpu->arch.sie_block->todpr = 0;
+ vcpu->arch.sie_block->cpnc = 0;
}
}

@@ -3579,6 +3582,7 @@ static void kvm_arch_vcpu_ioctl_clear_reset(struct kvm_vcpu *vcpu)

regs->etoken = 0;
regs->etoken_extension = 0;
+ regs->diag318 = 0;
}

int kvm_arch_vcpu_ioctl_set_regs(struct kvm_vcpu *vcpu, struct kvm_regs *regs)
@@ -4194,6 +4198,10 @@ static void sync_regs_fmt2(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
if (vcpu->arch.pfault_token == KVM_S390_PFAULT_TOKEN_INVALID)
kvm_clear_async_pf_completion_queue(vcpu);
}
+ if (kvm_run->kvm_dirty_regs & KVM_SYNC_DIAG318) {
+ vcpu->arch.diag318_info.val = kvm_run->s.regs.diag318;
+ vcpu->arch.sie_block->cpnc = vcpu->arch.diag318_info.cpnc;
+ }
/*
* If userspace sets the riccb (e.g. after migration) to a valid state,
* we should enable RI here instead of doing the lazy enablement.
@@ -4295,6 +4303,7 @@ static void store_regs_fmt2(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run)
kvm_run->s.regs.pp = vcpu->arch.sie_block->pp;
kvm_run->s.regs.gbea = vcpu->arch.sie_block->gbea;
kvm_run->s.regs.bpbc = (vcpu->arch.sie_block->fpf & FPF_BPBC) == FPF_BPBC;
+ kvm_run->s.regs.diag318 = vcpu->arch.diag318_info.val;
if (MACHINE_HAS_GS) {
__ctl_set_bit(2, 4);
if (vcpu->arch.gs_enabled)
diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index 9e9056cebfcf..4f3cbf6003a9 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -548,6 +548,7 @@ static int shadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
scb_s->ecd |= scb_o->ecd & ECD_ETOKENF;

scb_s->hpid = HPID_VSIE;
+ scb_s->cpnc = scb_o->cpnc;

prepare_ibc(vcpu, vsie_page);
rc = shadow_crycb(vcpu, vsie_page);
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 4fdf30316582..35cdb4307904 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1031,6 +1031,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_PPC_SECURE_GUEST 181
#define KVM_CAP_HALT_POLL 182
#define KVM_CAP_ASYNC_PF_INT 183
+#define KVM_CAP_S390_DIAG318 184

#ifdef KVM_CAP_IRQ_ROUTING

--
2.26.2