On 03/01/2018 04:35 AM, David Hildenbrand wrote:
On 28.02.2018 21:39, Tony Krowiak wrote:
On 02/28/2018 04:44 AM, David Hildenbrand wrote:
On 27.02.2018 15:28, Tony Krowiak wrote:
Introduces a new interface to enable AP interpretive
execution (IE) mode for the KVM guest. When running
with IE mode enabled, AP instructions executed on the
KVM guest will be interpreted by the firmware and
passed directly through to an AP device installed on
the system. The CPU model feature for AP must
be enabled for the KVM guest in order to enable
interpretive execution mode.
This interface will be used in a subsequent patch
by the VFIO AP device driver.
Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxxxxxxx>
---
arch/s390/include/asm/kvm-ap.h | 2 ++
arch/s390/include/asm/kvm_host.h | 1 +
arch/s390/kvm/kvm-ap.c | 27 +++++++++++++++++++++++++++
arch/s390/kvm/kvm-s390.h | 1 +
4 files changed, 31 insertions(+), 0 deletions(-)
diff --git a/arch/s390/include/asm/kvm-ap.h b/arch/s390/include/asm/kvm-ap.h
index 46e7c5b..6bd6bfb 100644
--- a/arch/s390/include/asm/kvm-ap.h
+++ b/arch/s390/include/asm/kvm-ap.h
@@ -51,4 +51,6 @@ struct kvm_ap_matrix {
void kvm_ap_deconfigure_matrix(struct kvm *kvm);
+int kvm_ap_enable_ie_mode(struct kvm *kvm);
+
#endif /* _ASM_KVM_AP */
diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index a4c77d3..1eebdd6 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -186,6 +186,7 @@ struct kvm_s390_sie_block {
#define ECA_AIV 0x00200000
#define ECA_VX 0x00020000
#define ECA_PROTEXCI 0x00002000
+#define ECA_APIE 0x00000008
#define ECA_SII 0x00000001
__u32 eca; /* 0x004c */
#define ICPT_INST 0x04
diff --git a/arch/s390/kvm/kvm-ap.c b/arch/s390/kvm/kvm-ap.c
index bb29045..862e54b 100644
--- a/arch/s390/kvm/kvm-ap.c
+++ b/arch/s390/kvm/kvm-ap.c
@@ -307,3 +307,30 @@ void kvm_ap_deconfigure_matrix(struct kvm *kvm)
kvm_ap_clear_crycb_masks(kvm);
}
EXPORT_SYMBOL(kvm_ap_deconfigure_matrix);
+
+/**
+ * kvm_ap_enable_ie_mode
+ *
+ * Enable interpretrive execution of AP instructions for the guest. When
+ * enabled, AP instructions executed on the guest will be interpreted and
+ * passed through to an AP installed on the host system.
+ *
+ * Returns 0 if interpretrive execution is enabled. Returns -EOPNOTSUPP
+ * if AP facilities are not installed for the guest.
+ *
+ * @kvm: the guest's kvm structure
+ */
+int kvm_ap_enable_ie_mode(struct kvm *kvm)
+{
+ int i;
+ struct kvm_vcpu *vcpu;
+
+ if (!test_kvm_cpu_feat(kvm, KVM_S390_VM_CPU_FEAT_AP))
+ return -EOPNOTSUPP;
+
+ kvm_for_each_vcpu(i, vcpu, kvm)
+ vcpu->arch.sie_block->eca |= ECA_APIE;
+
+ return 0;
+}
+EXPORT_SYMBOL(kvm_ap_enable_ie_mode);
diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index 1b5621f..3142541 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -18,6 +18,7 @@
#include <asm/facility.h>
#include <asm/processor.h>
#include <asm/sclp.h>
+#include <asm/ap.h>
/* Transactional Memory Execution related macros */
#define IS_TE_ENABLED(vcpu) ((vcpu->arch.sie_block->ecb & ECB_TE))
And also, what about hot-plugged CPUs?
I haven't considered that, do you have any suggestions?
You should handle the KVM_S390_VM_CPU_FEAT_AP feature instead during
kvm_arch_vcpu_setup(), independent of any configured AP devices.
This avoids the races I mentioned in regards to this series and also
will handle hotplugged CPUs properly.
If KVM_S390_VM_CPU_FEAT_AP is configured for a guest -> each CPU sets
ECA_APIE during kvm_arch_vcpu_setup().
We talked about this in a couple of other patches, but I am on
board with this. To make things clearer, Should we rename
the feature to KVM_S390_VM_CPU_FEAT_APIE so its purpose is more
clear?
(In the vSIE code, simply allow to set ECA_APIE in the shadow SCB in
case KVM_S390_VM_CPU_FEAT_AP is enabled)
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