Re: [PATCH 6/7] s390: vfio-ap: handle dynamic config/deconfig of AP adapter

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On 11/04/2019 23:03, Tony Krowiak wrote:
Once an APQN is assigned to an mdev device it will remained assigned until
it is explicitly unassigned from the mdev device. The associated AP queue
devices, however, can come and go due to failures or deliberate actions by
a sysadmin. For example, a sysadmin can dynamically remove an AP adapter
card using the SE or by executing an SCLP command. This patch refactors
the probe and remove callbacks of the vfio_ap driver to handle dynamic
changes as follows:

* Probe callback changes:

   If the APQN of the queue being probed is assigned to an mdev device, the
   mdev device is in use by a guest, and the APQN is not set in the guest's
   CRYCB, the CRYCB will be dynamically updated to give the guest access to
   the queue.

* Remove callback changes:

   If the APQN of the queue being removed is assigned to an mdev device,
   the mdev
   device is in use by a guest, and the APQN is set in the guest's CRYCB,
   the CRYCB will be dynamically updated to remove the guest's access to
   the adapter card associated with the queue. Keep in mind, the
   architecture does not provide a way to remove access to a single queue
   unless only one queue is in the guest's configuration, so it was decided
   that it makes more sense to unplug the adapter from the guest.

   The APQN of the queue being removed will remain assigned to the mdev
   device should the queue be dynamically returned to the configuration.
   The queue will also be reset prior to returning control to the caller
   (a.k.a., the AP bus).

Signed-off-by: Tony Krowiak <akrowiak@xxxxxxxxxxxxx>
---
  arch/s390/include/asm/kvm_host.h      |  2 ++
  arch/s390/kvm/kvm-s390.c              | 37 +++++++++++++++++++
  drivers/s390/crypto/vfio_ap_drv.c     | 16 +++++++--
  drivers/s390/crypto/vfio_ap_ops.c     | 67 +++++++++++++++++++++++++++++++++--
  drivers/s390/crypto/vfio_ap_private.h |  2 ++
  5 files changed, 120 insertions(+), 4 deletions(-)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index c47e22bba87f..0ce5d9b0df59 100644kvm_s390_crypto_cb
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -895,6 +895,8 @@ void kvm_arch_async_page_present(struct kvm_vcpu *vcpu,
  void kvm_arch_crypto_clear_masks(struct kvm *kvm);
  void kvm_arch_crypto_set_masks(struct kvm *kvm, unsigned long *apm,
  			       unsigned long *aqm, unsigned long *adm);
+int kvm_arch_crypto_test_masks(struct kvm *kvm, unsigned long *apm,
+			       unsigned long *aqm, unsigned long *adm);
extern int sie64a(struct kvm_s390_sie_block *, u64 *);
  extern char sie_exit;
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 4638303ba6a8..5f423cdd29ba 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2217,6 +2217,43 @@ static void kvm_s390_set_crycb_format(struct kvm *kvm)
  		kvm->arch.crypto.crycbd |= CRYCB_FORMAT1;
  }

This function requires the big matrix lock, may be add a comment.

+int kvm_arch_crypto_test_masks(struct kvm *kvm, unsigned long *apm,
+			       unsigned long *aqm, unsigned long *adm)
+{
+	int ret;
+	struct kvm_s390_crypto_cb *crycb = kvm->arch.crypto.crycb;
+
+	switch (kvm->arch.crypto.crycbd & CRYCB_FORMAT_MASK) {
+	case CRYCB_FORMAT2: /* APCB1 use 256 bits */
+		ret = bitmap_equal(apm, (unsigned long *)crycb->apcb1.apm, 256);
+		VM_EVENT(kvm, 3, "TEST CRYCB: apm %016lx %016lx %016lx %016lx",
+			 apm[0], apm[1], apm[2], apm[3]);
+		ret &= bitmap_equal(aqm,
+				    (unsigned long *)crycb->apcb1.aqm, 256);
+		VM_EVENT(kvm, 3, "TEST CRYCB: aqm %016lx %016lx %016lx %016lx",
+			 aqm[0], aqm[1], aqm[2], aqm[3]);
+		ret &= bitmap_equal(adm,
+				    (unsigned long *)crycb->apcb1.adm, 256);
+		VM_EVENT(kvm, 3, "TEST CRYCB: adm %016lx %016lx %016lx %016lx",
+			 adm[0], adm[1], adm[2], adm[3]);
+		break;
+	case CRYCB_FORMAT1:
+	case CRYCB_FORMAT0: /* Fall through both use APCB0 */
+		ret = bitmap_equal(apm, (unsigned long *)crycb->apcb1.apm, 64);
+		ret &= bitmap_equal(aqm, (unsigned long *)crycb->apcb1.aqm, 16);
+		ret &= bitmap_equal(adm, (unsigned long *)crycb->apcb1.adm, 16);
+		VM_EVENT(kvm, 3, "TEST CRYCB: apm %016lx aqm %04x adm %04x",
+			 apm[0], *((unsigned short *)aqm),
+			 *((unsigned short *)adm));
+		break;
+	default:	/* Can not happen */
+		ret = 0;
+		break;
+	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(kvm_arch_crypto_test_masks);

Wouldn't it be interesting to work on the ap_matrix structure instead of on the real CRYCB?
You could spare a lot of tests and wouldn't require to change this file.

Regards,
Pierre


--
Pierre Morel
Linux/KVM/QEMU in Böblingen - Germany




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