Hi all,
@Claudio, I kept your reviewed-by because I think the changes
are only cosmetics... of course tell me if it is right.
This new series add the implementation of interpretation for
the PTF instruction.
The series provides:
1- interception of the STSI instruction forwarding the CPU topology
2- interpretation of the PTF instruction
3- a KVM capability for the userland hypervisor to ask KVM to
setup PTF interpretation.
0- Foreword
The S390 CPU topology is reported using two instructions:
- PTF, to get information if the CPU topology did change since last
PTF instruction or a subsystem reset.
- STSI, to get the topology information, consisting of the topology
of the CPU inside the sockets, of the sockets inside the books etc.
The PTF(2) instruction report a change if the STSI(15.1.2) instruction
will report a difference with the last STSI(15.1.2) instruction*.
With the SIE interpretation, the PTF(2) instruction will report a
change to the guest if the host sets the SCA.MTCR bit.
*The STSI(15.1.2) instruction reports:
- The cores address within a socket
- The polarization of the cores
- The CPU type of the cores
- If the cores are dedicated or not
We decided to implement the CPU topology for S390 in several steps:
- first we report CPU hotplug
- modification of the CPU mask inside sockets
In future development we will provide:
- handling of shared CPUs
- reporting of the CPU Type
- reporting of the polarization
1- Interception of STSI
To provide Topology information to the guest through the STSI
instruction, we forward STSI with Function Code 15 to the
userland hypervisor which will take care to provide the right
information to the guest.
To let the guest use both the PTF instruction to check if a topology
change occurred and sthe STSI_15.x.x instruction we add a new KVM
capability to enable the topology facility.
2- Interpretation of PTF with FC(2)
The PTF instruction will report a topology change if there is any change
with a previous STSI(15.1.2) SYSIB.
Changes inside a STSI(15.1.2) SYSIB occur if CPU bits are set or clear
inside the CPU Topology List Entry CPU mask field, which happens with
changes in CPU polarization, dedication, CPU types and adding or
removing CPUs in a socket.
The reporting to the guest is done using the Multiprocessor
Topology-Change-Report (MTCR) bit of the utility entry of the guest's
SCA which will be cleared during the interpretation of PTF.
To check if the topology has been modified we use a new field of the
arch vCPU prev_cpu, to save the previous real CPU ID at the end of a
schedule and verify on next schedule that the CPU used is in the same
socket, this field is initialized to -1 on vCPU creation.
Regards,
Pierre
Pierre Morel (1):
s390x: KVM: guest support for topology function
Documentation/virt/kvm/api.rst | 16 +++++++++++
arch/s390/include/asm/kvm_host.h | 12 ++++++--
arch/s390/kvm/kvm-s390.c | 48 +++++++++++++++++++++++++++++++-
arch/s390/kvm/kvm-s390.h | 25 +++++++++++++++++
arch/s390/kvm/priv.c | 14 +++++++---
arch/s390/kvm/vsie.c | 3 ++
include/uapi/linux/kvm.h | 1 +
7 files changed, 111 insertions(+), 8 deletions(-)
--
2.27.0
Changelog:
from v5 to v6
- make the subject more accurate
(Claudio)
- Change the kvm_s390_set_mtcr() function to have vcpu in the name
(Janosch)
- Replace the checks on ECB_PTF wit the check of facility 11
(Janosch)
- modify kvm_arch_vcpu_load, move the check in a function in
the header file
(Janosh)
- No magical number replace the "new cpu value" of -1 with a define
(Janosch)
- Make the checks for STSI validity clearer
(Janosch)
from v4 tp v5
- modify the way KVM_CAP is tested to be OK with vsie
(David)
from v3 to v4
- squatch both patches
(David)
- Added Documentation
(David)
- Modified the detection for new vCPUs
(Pierre)
from v2 to v3
- use PTF interpretation
(Christian)
- optimize arch_update_cpu_topology using PTF
(Pierre)
from v1 to v2:
- Add a KVM capability to let QEMU know we support PTF and STSI 15
(David)
- check KVM facility 11 before accepting STSI fc 15
(David)
- handle all we can in userland
(David)
- add tracing to STSI fc 15
(Connie)
We let the userland hypervisor know if the machine support the CPU
topology facility using a new KVM capability: KVM_CAP_S390_CPU_TOPOLOGY.
The PTF instruction will report a topology change if there is any change
with a previous STSI_15_1_2 SYSIB.
Changes inside a STSI_15_1_2 SYSIB occur if CPU bits are set or clear
inside the CPU Topology List Entry CPU mask field, which happens with
changes in CPU polarization, dedication, CPU types and adding or
removing CPUs in a socket.
The reporting to the guest is done using the Multiprocessor
Topology-Change-Report (MTCR) bit of the utility entry of the guest's
SCA which will be cleared during the interpretation of PTF.
To check if the topology has been modified we use a new field of the
arch vCPU to save the previous real CPU ID at the end of a schedule
and verify on next schedule that the CPU used is in the same socket.
We do not report polarization, CPU Type or dedication change.
STSI(15.1.x) gives information on the CPU configuration topology.
Let's accept the interception of STSI with the function code 15 and
let the userland part of the hypervisor handle it when userland
support the CPU Topology facility.
Signed-off-by: Pierre Morel <[email protected]>
Reviewed-by: Claudio Imbrenda <[email protected]>
---
Documentation/virt/kvm/api.rst | 16 +++++++++++
arch/s390/include/asm/kvm_host.h | 12 ++++++--
arch/s390/kvm/kvm-s390.c | 48 +++++++++++++++++++++++++++++++-
arch/s390/kvm/kvm-s390.h | 25 +++++++++++++++++
arch/s390/kvm/priv.c | 14 +++++++---
arch/s390/kvm/vsie.c | 3 ++
include/uapi/linux/kvm.h | 1 +
7 files changed, 111 insertions(+), 8 deletions(-)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index aeeb071c7688..81038429d6db 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -7484,3 +7484,19 @@ The argument to KVM_ENABLE_CAP is also a bitmask, and must be a subset
of the result of KVM_CHECK_EXTENSION. KVM will forward to userspace
the hypercalls whose corresponding bit is in the argument, and return
ENOSYS for the others.
+
+8.17 KVM_CAP_S390_CPU_TOPOLOGY
+------------------------------
+
+:Capability: KVM_CAP_S390_CPU_TOPOLOGY
+:Architectures: s390
+:Type: vm
+
+This capability indicates that kvm will provide the S390 CPU Topology facility
+which consist of the interpretation of the PTF instruction for the Function
+Code 2 along with interception and forwarding of both the PTF instruction
+with Function Codes 0 or 1 and the STSI(15,1,x) instruction to the userland
+hypervisor.
+
+The stfle facility 11, CPU Topology facility, should not be provided to the
+guest without this capability.
diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index a604d51acfc8..df039b9f0a39 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -95,15 +95,19 @@ struct bsca_block {
union ipte_control ipte_control;
__u64 reserved[5];
__u64 mcn;
- __u64 reserved2;
+#define ESCA_UTILITY_MTCR 0x8000
+ __u16 utility;
+ __u8 reserved2[6];
struct bsca_entry cpu[KVM_S390_BSCA_CPU_SLOTS];
};
struct esca_block {
union ipte_control ipte_control;
- __u64 reserved1[7];
+ __u64 reserved1[6];
+ __u16 utility;
+ __u8 reserved2[6];
__u64 mcn[4];
- __u64 reserved2[20];
+ __u64 reserved3[20];
struct esca_entry cpu[KVM_S390_ESCA_CPU_SLOTS];
};
@@ -247,6 +251,7 @@ struct kvm_s390_sie_block {
#define ECB_SPECI 0x08
#define ECB_SRSI 0x04
#define ECB_HOSTPROTINT 0x02
+#define ECB_PTF 0x01
__u8 ecb; /* 0x0061 */
#define ECB2_CMMA 0x80
#define ECB2_IEP 0x20
@@ -748,6 +753,7 @@ struct kvm_vcpu_arch {
bool skey_enabled;
struct kvm_s390_pv_vcpu pv;
union diag318_info diag318_info;
+ int prev_cpu;
};
struct kvm_vm_stat {
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 14a18ba5ff2c..b7424a6b9263 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -606,6 +606,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_S390_PROTECTED:
r = is_prot_virt_host();
break;
+ case KVM_CAP_S390_CPU_TOPOLOGY:
+ r = test_facility(11);
+ break;
default:
r = 0;
}
@@ -817,6 +820,20 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
icpt_operexc_on_all_vcpus(kvm);
r = 0;
break;
+ case KVM_CAP_S390_CPU_TOPOLOGY:
+ r = -EINVAL;
+ mutex_lock(&kvm->lock);
+ if (kvm->created_vcpus) {
+ r = -EBUSY;
+ } else if (test_facility(11)) {
+ set_kvm_facility(kvm->arch.model.fac_mask, 11);
+ set_kvm_facility(kvm->arch.model.fac_list, 11);
+ r = 0;
+ }
+ mutex_unlock(&kvm->lock);
+ VM_EVENT(kvm, 3, "ENABLE: CPU TOPOLOGY %s",
+ r ? "(not available)" : "(success)");
+ break;
default:
r = -EINVAL;
break;
@@ -3089,18 +3106,40 @@ __u64 kvm_s390_get_cpu_timer(struct kvm_vcpu *vcpu)
return value;
}
-void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
+/**
+ * kvm_s390_vcpu_set_mtcr
+ * @vcp: the virtual CPU
+ *
+ * Is only relevant if the topology facility is present.
+ *
+ * Updates the Multiprocessor Topology-Change-Report to signal
+ * the guest with a topology change.
+ */
+static void kvm_s390_vcpu_set_mtcr(struct kvm_vcpu *vcpu)
{
+ struct esca_block *esca = vcpu->kvm->arch.sca;
+
+ ipte_lock(vcpu);
+ WRITE_ONCE(esca->utility, ESCA_UTILITY_MTCR);
+ ipte_unlock(vcpu);
+}
+void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
+{
gmap_enable(vcpu->arch.enabled_gmap);
kvm_s390_set_cpuflags(vcpu, CPUSTAT_RUNNING);
if (vcpu->arch.cputm_enabled && !is_vcpu_idle(vcpu))
__start_cpu_timer_accounting(vcpu);
vcpu->cpu = cpu;
+
+ if (kvm_s390_topology_changed(vcpu))
+ kvm_s390_vcpu_set_mtcr(vcpu);
}
void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)
{
+ /* Remember which CPU was backing the vCPU */
+ vcpu->arch.prev_cpu = vcpu->cpu;
vcpu->cpu = -1;
if (vcpu->arch.cputm_enabled && !is_vcpu_idle(vcpu))
__stop_cpu_timer_accounting(vcpu);
@@ -3220,6 +3259,13 @@ static int kvm_s390_vcpu_setup(struct kvm_vcpu *vcpu)
vcpu->arch.sie_block->ecb |= ECB_HOSTPROTINT;
if (test_kvm_facility(vcpu->kvm, 9))
vcpu->arch.sie_block->ecb |= ECB_SRSI;
+
+ /* PTF needs guest facilities to enable interpretation */
+ if (test_kvm_facility(vcpu->kvm, 11))
+ vcpu->arch.sie_block->ecb |= ECB_PTF;
+ /* Indicate this is a new vcpu */
+ vcpu->arch.prev_cpu = S390_KVM_TOPOLOGY_NEW_CPU;
+
if (test_kvm_facility(vcpu->kvm, 73))
vcpu->arch.sie_block->ecb |= ECB_TE;
if (!kvm_is_ucontrol(vcpu->kvm))
diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index c07a050d757d..f664d120a5aa 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -488,4 +488,29 @@ void kvm_s390_vcpu_crypto_reset_all(struct kvm *kvm);
*/
extern unsigned int diag9c_forwarding_hz;
+#define S390_KVM_TOPOLOGY_NEW_CPU -1
+/**
+ * kvm_s390_topology_changed
+ * @vcpu: the virtual CPU
+ *
+ * If the topology facility is present, checks if the CPU toplogy
+ * viewed by the guest changed due to load balancing or CPU hotplug.
+ */
+static inline bool kvm_s390_topology_changed(struct kvm_vcpu *vcpu)
+{
+ if (!test_kvm_facility(vcpu->kvm, 11))
+ return false;
+
+ /* A new vCPU has been hotplugged */
+ if (vcpu->arch.prev_cpu == S390_KVM_TOPOLOGY_NEW_CPU)
+ return true;
+
+ /* The real CPU backing up the vCPU moved to another socket */
+ if (topology_physical_package_id(vcpu->cpu) !=
+ topology_physical_package_id(vcpu->arch.prev_cpu))
+ return true;
+
+ return false;
+}
+
#endif
diff --git a/arch/s390/kvm/priv.c b/arch/s390/kvm/priv.c
index 417154b314a6..5ff6be498cbd 100644
--- a/arch/s390/kvm/priv.c
+++ b/arch/s390/kvm/priv.c
@@ -861,10 +861,12 @@ static int handle_stsi(struct kvm_vcpu *vcpu)
if (vcpu->arch.sie_block->gpsw.mask & PSW_MASK_PSTATE)
return kvm_s390_inject_program_int(vcpu, PGM_PRIVILEGED_OP);
- if (fc > 3) {
- kvm_s390_set_psw_cc(vcpu, 3);
- return 0;
- }
+ if (fc > 3 && fc != 15)
+ goto out_no_data;
+
+ /* fc 15 is provided with PTF/CPU topology support */
+ if (fc == 15 && !test_kvm_facility(vcpu->kvm, 11))
+ goto out_no_data;
if (vcpu->run->s.regs.gprs[0] & 0x0fffff00
|| vcpu->run->s.regs.gprs[1] & 0xffff0000)
@@ -898,6 +900,10 @@ static int handle_stsi(struct kvm_vcpu *vcpu)
goto out_no_data;
handle_stsi_3_2_2(vcpu, (void *) mem);
break;
+ case 15:
+ trace_kvm_s390_handle_stsi(vcpu, fc, sel1, sel2, operand2);
+ insert_stsi_usr_data(vcpu, operand2, ar, fc, sel1, sel2);
+ return -EREMOTE;
}
if (kvm_s390_pv_cpu_is_protected(vcpu)) {
memcpy((void *)sida_origin(vcpu->arch.sie_block), (void *)mem,
diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c
index acda4b6fc851..da0397cf2cc7 100644
--- a/arch/s390/kvm/vsie.c
+++ b/arch/s390/kvm/vsie.c
@@ -503,6 +503,9 @@ static int shadow_scb(struct kvm_vcpu *vcpu, struct vsie_page *vsie_page)
/* Host-protection-interruption introduced with ESOP */
if (test_kvm_cpu_feat(vcpu->kvm, KVM_S390_VM_CPU_FEAT_ESOP))
scb_s->ecb |= scb_o->ecb & ECB_HOSTPROTINT;
+ /* CPU Topology */
+ if (test_kvm_facility(vcpu->kvm, 11))
+ scb_s->ecb |= scb_o->ecb & ECB_PTF;
/* transactional execution */
if (test_kvm_facility(vcpu->kvm, 73) && wants_tx) {
/* remap the prefix is tx is toggled on */
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index 1daa45268de2..273c62dfbe9a 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1131,6 +1131,7 @@ struct kvm_ppc_resize_hpt {
#define KVM_CAP_EXIT_ON_EMULATION_FAILURE 204
#define KVM_CAP_ARM_MTE 205
#define KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM 206
+#define KVM_CAP_S390_CPU_TOPOLOGY 207
#ifdef KVM_CAP_IRQ_ROUTING
--
2.27.0