[PATCH v5 07/10] kvm: s390: Add CPU dump functionality

Janosch Frank
2022-05-16T09:09:59Z

The previous patch introduced the per-VM dump functions now let's
focus on dumping the VCPU state via the newly introduced
KVM_S390_PV_CPU_COMMAND ioctl which mirrors the VM UV ioctl and can be
extended with new commands later.

Signed-off-by: Janosch Frank <frankja@linux.ibm.com>
---
arch/s390/kvm/kvm-s390.c | 73 ++++++++++++++++++++++++++++++++++++++++
arch/s390/kvm/kvm-s390.h | 1 +
arch/s390/kvm/pv.c | 16 +++++++++
include/uapi/linux/kvm.h | 4 +++
4 files changed, 94 insertions(+)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 6bf9dd85d50f..c0c848c84552 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -5129,6 +5129,52 @@ long kvm_arch_vcpu_async_ioctl(struct file *filp,
return -ENOIOCTLCMD;
}

+static int kvm_s390_handle_pv_vcpu_dump(struct kvm_vcpu *vcpu,
+ struct kvm_pv_cmd *cmd)
+{
+ struct kvm_s390_pv_dmp dmp;
+ void *data;
+ int ret;
+
+ /* Dump initialization is a prerequisite */
+ if (!vcpu->kvm->arch.pv.dumping)
+ return -EINVAL;
+
+ if (copy_from_user(&dmp, (__u8 __user *)cmd->data, sizeof(dmp)))
+ return -EFAULT;
+
+ /* We only handle this subcmd right now */
+ if (dmp.subcmd != KVM_PV_DUMP_CPU)
+ return -EINVAL;
+
+ /* CPU dump length is the same as create cpu storage donation. */
+ if (dmp.buff_len != uv_info.guest_cpu_stor_len)
+ return -EINVAL;
+
+ data = vzalloc(uv_info.guest_cpu_stor_len);
+ if (!data)
+ return -ENOMEM;
+
+ ret = kvm_s390_pv_dump_cpu(vcpu, data, &cmd->rc, &cmd->rrc);
+
+ VCPU_EVENT(vcpu, 3, "PROTVIRT DUMP CPU %d rc %x rrc %x",
+ vcpu->vcpu_id, cmd->rc, cmd->rrc);
+
+ if (ret) {
+ vfree(data);
+ return -EINVAL;
+ }
+
+ /* On success copy over the dump data */
+ if (copy_to_user((__u8 __user *)dmp.buff_addr, data, uv_info.guest_cpu_stor_len)) {
+ vfree(data);
+ return -EFAULT;
+ }
+
+ vfree(data);
+ return 0;
+}
+
long kvm_arch_vcpu_ioctl(struct file *filp,
unsigned int ioctl, unsigned long arg)
{
@@ -5293,6 +5339,33 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
irq_state.len);
break;
}
+ case KVM_S390_PV_CPU_COMMAND: {
+ struct kvm_pv_cmd cmd;
+
+ r = -EINVAL;
+ if (!is_prot_virt_host())
+ break;
+
+ r = -EFAULT;
+ if (copy_from_user(&cmd, argp, sizeof(cmd)))
+ break;
+
+ r = -EINVAL;
+ if (cmd.flags)
+ break;
+
+ /* We only handle this cmd right now */
+ if (cmd.cmd != KVM_PV_DUMP)
+ break;
+
+ r = kvm_s390_handle_pv_vcpu_dump(vcpu, &cmd);
+
+ /* Always copy over UV rc / rrc data */
+ if (copy_to_user((__u8 __user *)argp, &cmd.rc,
+ sizeof(cmd.rc) + sizeof(cmd.rrc)))
+ r = -EFAULT;
+ break;
+ }
default:
r = -ENOTTY;
}
diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index 2868dd0bba25..a39815184350 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -250,6 +250,7 @@ int kvm_s390_pv_set_sec_parms(struct kvm *kvm, void *hdr, u64 length, u16 *rc,
int kvm_s390_pv_unpack(struct kvm *kvm, unsigned long addr, unsigned long size,
unsigned long tweak, u16 *rc, u16 *rrc);
int kvm_s390_pv_set_cpu_state(struct kvm_vcpu *vcpu, u8 state);
+int kvm_s390_pv_dump_cpu(struct kvm_vcpu *vcpu, void *buff, u16 *rc, u16 *rrc);
int kvm_s390_pv_dump_stor_state(struct kvm *kvm, void __user *buff_user,
u64 *gaddr, u64 buff_user_len, u16 *rc, u16 *rrc);

diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
index fd261667d2c2..8c72330efc0e 100644
--- a/arch/s390/kvm/pv.c
+++ b/arch/s390/kvm/pv.c
@@ -300,6 +300,22 @@ int kvm_s390_pv_set_cpu_state(struct kvm_vcpu *vcpu, u8 state)
return 0;
}

+int kvm_s390_pv_dump_cpu(struct kvm_vcpu *vcpu, void *buff, u16 *rc, u16 *rrc)
+{
+ struct uv_cb_dump_cpu uvcb = {
+ .header.cmd = UVC_CMD_DUMP_CPU,
+ .header.len = sizeof(uvcb),
+ .cpu_handle = vcpu->arch.pv.handle,
+ .dump_area_origin = (u64)buff,
+ };
+ int cc;
+
+ cc = uv_call_sched(0, (u64)&uvcb);
+ *rc = uvcb.header.rc;
+ *rrc = uvcb.header.rrc;
+ return cc;
+}
+
/* Size of the cache for the storage state dump data. 1MB for now */
#define DUMP_BUFF_LEN HPAGE_SIZE

diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 1c60c2d314ba..0a8b57654ea7 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1657,6 +1657,7 @@ enum pv_cmd_dmp_id {
KVM_PV_DUMP_INIT,
KVM_PV_DUMP_CONFIG_STOR_STATE,
KVM_PV_DUMP_COMPLETE,
+ KVM_PV_DUMP_CPU,
};

struct kvm_s390_pv_dmp {
@@ -2118,4 +2119,7 @@ struct kvm_stats_desc {
/* Available with KVM_CAP_XSAVE2 */
#define KVM_GET_XSAVE2 _IOR(KVMIO, 0xcf, struct kvm_xsave)

+/* Available with KVM_CAP_S390_PROTECTED_DUMP */
+#define KVM_S390_PV_CPU_COMMAND _IOWR(KVMIO, 0xd0, struct kvm_pv_cmd)
+
#endif /* __LINUX_KVM_H */
--
2.34.1