Re: [PATCH 19/32] KVM: s390: mechanism to enable guest zPCI Interpretation

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Am 07.12.21 um 21:57 schrieb Matthew Rosato:
The guest must have access to certain facilities in order to allow
interpretive execution of zPCI instructions and adapter event
notifications.  However, there are some cases where a guest might
disable interpretation -- provide a mechanism via which we can defer
enabling the associated zPCI interpretation facilities until the guest
indicates it wishes to use them.

Signed-off-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
---
  arch/s390/include/asm/kvm_host.h |  4 +++
  arch/s390/kvm/kvm-s390.c         | 43 ++++++++++++++++++++++++++++++++
  arch/s390/kvm/kvm-s390.h         | 10 ++++++++
  3 files changed, 57 insertions(+)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 3f147b8d050b..38982c1de413 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -252,7 +252,10 @@ struct kvm_s390_sie_block {
  #define ECB2_IEP	0x20
  #define ECB2_PFMFI	0x08
  #define ECB2_ESCA	0x04
+#define ECB2_ZPCI_LSI	0x02
  	__u8    ecb2;                   /* 0x0062 */
+#define ECB3_AISI	0x20
+#define ECB3_AISII	0x10
  #define ECB3_DEA 0x08
  #define ECB3_AES 0x04
  #define ECB3_RI  0x01
@@ -938,6 +941,7 @@ struct kvm_arch{
  	int use_cmma;
  	int use_pfmfi;
  	int use_skf;
+	int use_zpci_interp;
  	int user_cpu_state_ctrl;
  	int user_sigp;
  	int user_stsi;
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index a680f2a02b67..361d742cdf0d 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -1023,6 +1023,47 @@ static int kvm_s390_vm_set_crypto(struct kvm *kvm, struct kvm_device_attr *attr)
  	return 0;
  }
+static void kvm_s390_vcpu_pci_setup(struct kvm_vcpu *vcpu)
+{
+	/*
+	 * If the facilities aren't available for PCI interpretation and
+	 * interrupt forwarding, we shouldn't be here.
+	 */

This reads like we want a WARN_ON or BUG_ON, but as we call this uncoditionally this is
actually a valid check. So instead of "shouldn't be here" say something like "bail out
if interpretion is not active".  ?

+	if (!vcpu->kvm->arch.use_zpci_interp)
+		return;
+
+	vcpu->arch.sie_block->ecb2 |= ECB2_ZPCI_LSI;
+	vcpu->arch.sie_block->ecb3 |= ECB3_AISII + ECB3_AISI;
+}
+
+void kvm_s390_vcpu_pci_enable_interp(struct kvm *kvm)
+{
+	struct kvm_vcpu *vcpu;
+	int i;
+
+	/*
+	 * If host facilities are available, turn on interpretation for the
+	 * life of this guest
+	 */
+	if (!test_facility(69) || !test_facility(70) || !test_facility(71) ||
+	    !test_facility(72))
+		return;

Wouldnt that also enable interpretion for VSIE? I guess we should check for the
sclp facilities from patches 1,2,3, and 4 instead.


+
+	mutex_lock(&kvm->lock);
+
+	kvm->arch.use_zpci_interp = 1;
+
+	kvm_s390_vcpu_block_all(kvm);
+
+	kvm_for_each_vcpu(i, vcpu, kvm) {
+		kvm_s390_vcpu_pci_setup(vcpu);
+		kvm_s390_sync_request(KVM_REQ_VSIE_RESTART, vcpu);
+	}
+
+	kvm_s390_vcpu_unblock_all(kvm);
+	mutex_unlock(&kvm->lock);
+}
+
  static void kvm_s390_sync_request_broadcast(struct kvm *kvm, int req)
  {
  	int cx;
@@ -3288,6 +3329,8 @@ static int kvm_s390_vcpu_setup(struct kvm_vcpu *vcpu)
  h
  	kvm_s390_vcpu_crypto_setup(vcpu);
+ kvm_s390_vcpu_pci_setup(vcpu);
+
  	mutex_lock(&vcpu->kvm->lock);
  	if (kvm_s390_pv_is_protected(vcpu->kvm)) {
  		rc = kvm_s390_pv_create_cpu(vcpu, &uvrc, &uvrrc);
diff --git a/arch/s390/kvm/kvm-s390.h b/arch/s390/kvm/kvm-s390.h
index c07a050d757d..a2eccb8b977e 100644
--- a/arch/s390/kvm/kvm-s390.h
+++ b/arch/s390/kvm/kvm-s390.h
@@ -481,6 +481,16 @@ void kvm_s390_reinject_machine_check(struct kvm_vcpu *vcpu,
   */
  void kvm_s390_vcpu_crypto_reset_all(struct kvm *kvm);
+/**
+ * kvm_s390_vcpu_pci_enable_interp
+ *
+ * Set the associated PCI attributes for each vcpu to allow for zPCI Load/Store
+ * interpretation as well as adapter interruption forwarding.
+ *
+ * @kvm: the KVM guest
+ */
+void kvm_s390_vcpu_pci_enable_interp(struct kvm *kvm);
+
  /**
   * diag9c_forwarding_hz
   *




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