[PATCH v6 15/21] KVM: s390: pci: add routines to start/stop interpretive execution

Matthew Rosato
2022-04-26T20:12:39Z

These routines will be invoked at the time an s390x vfio-pci device is
associated with a KVM (or when the association is removed), allowing
the zPCI device to enable or disable load/store intepretation mode;
this requires the host zPCI device to inform firmware of the unique
token (GISA designation) that is associated with the owning KVM.

Furthemore, add/remove these devices from a list associated with the
kvm and ensure proper cleanup always occurs during vm exit.

Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
---
arch/s390/include/asm/kvm_host.h | 13 +++
arch/s390/kvm/kvm-s390.c | 9 ++
arch/s390/kvm/pci.c | 158 +++++++++++++++++++++++++++++++
arch/s390/kvm/pci.h | 5 +
arch/s390/pci/pci.c | 3 +
5 files changed, 188 insertions(+)

diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
index 8e381603b6a7..cd58f204305e 100644
--- a/arch/s390/include/asm/kvm_host.h
+++ b/arch/s390/include/asm/kvm_host.h
@@ -19,6 +19,7 @@
#include <linux/kvm.h>
#include <linux/seqlock.h>
#include <linux/module.h>
+#include <linux/pci.h>
#include <asm/debug.h>
#include <asm/cpu.h>
#include <asm/fpu/api.h>
@@ -967,6 +968,8 @@ struct kvm_arch{
DECLARE_BITMAP(idle_mask, KVM_MAX_VCPUS);
struct kvm_s390_gisa_interrupt gisa_int;
struct kvm_s390_pv pv;
+ struct list_head kzdev_list;
+ spinlock_t kzdev_list_lock;
};

#define KVM_HVA_ERR_BAD (-1UL)
@@ -1017,4 +1020,14 @@ static inline void kvm_arch_flush_shadow_memslot(struct kvm *kvm,
static inline void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu) {}
static inline void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu) {}

+#ifdef CONFIG_PCI
+int kvm_s390_pci_register_kvm(struct zpci_dev *zdev, struct kvm *kvm);
+#else
+static inline int kvm_s390_pci_register_kvm(struct zpci_dev *dev,
+ struct kvm *kvm)
+{
+ return -EPERM;
+}
+#endif
+
#endif
diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index 504f312c1c27..bd6c8aeabc24 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -2866,6 +2866,13 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)

kvm_s390_crypto_init(kvm);

+ if (IS_ENABLED(CONFIG_VFIO_PCI)) {
+ mutex_lock(&kvm->lock);
+ kvm_s390_pci_init_list(kvm);
+ kvm_s390_vcpu_pci_enable_interp(kvm);
+ mutex_unlock(&kvm->lock);
+ }
+
mutex_init(&kvm->arch.float_int.ais_lock);
spin_lock_init(&kvm->arch.float_int.lock);
for (i = 0; i < FIRQ_LIST_COUNT; i++)
@@ -2951,6 +2958,8 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
if (!kvm_is_ucontrol(kvm))
gmap_remove(kvm->arch.gmap);
kvm_s390_destroy_adapters(kvm);
+ if (IS_ENABLED(CONFIG_VFIO_PCI))
+ kvm_s390_pci_clear_list(kvm);
kvm_s390_clear_float_irqs(kvm);
kvm_s390_vsie_destroy(kvm);
KVM_EVENT(3, "vm 0x%pK destroyed", kvm);
diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
index 72a9c6bfae86..2aee7f11db1d 100644
--- a/arch/s390/kvm/pci.c
+++ b/arch/s390/kvm/pci.c
@@ -12,7 +12,9 @@
#include <asm/pci.h>
#include <asm/pci_insn.h>
#include <asm/pci_io.h>
+#include <asm/sclp.h>
#include "pci.h"
+#include "kvm-s390.h"

struct zpci_aift *aift;

@@ -424,6 +426,162 @@ void kvm_s390_pci_dev_release(struct zpci_dev *zdev)
}
EXPORT_SYMBOL_GPL(kvm_s390_pci_dev_release);

+static inline int register_kvm(struct zpci_dev *zdev, struct kvm *kvm)
+{
+ int rc;
+
+ if (zdev->kzdev || zdev->gisa != 0)
+ return -EINVAL;
+
+ mutex_lock(&kvm->lock);
+
+ rc = kvm_s390_pci_dev_open(zdev);
+ if (rc)
+ goto err;
+
+ /*
+ * If interpretation facilities aren't available, add the device to
+ * the kzdev list but don't enable for interpretation.
+ */
+ if (!kvm_s390_pci_interp_allowed())
+ goto out;
+
+ /*
+ * If this is the first request to use an interpreted device, make the
+ * necessary vcpu changes
+ */
+ if (!kvm->arch.use_zpci_interp)
+ kvm_s390_vcpu_pci_enable_interp(kvm);
+
+ if (zdev_enabled(zdev)) {
+ rc = zpci_disable_device(zdev);
+ if (rc)
+ goto err;
+ }
+
+ /*
+ * Store information about the identity of the kvm guest allowed to
+ * access this device via interpretation to be used by host CLP
+ */
+ zdev->gisa = (u32)virt_to_phys(&kvm->arch.sie_page2->gisa);
+
+ rc = zpci_enable_device(zdev);
+ if (rc)
+ goto clear_gisa;
+
+ /* Re-register the IOMMU that was already created */
+ rc = zpci_register_ioat(zdev, 0, zdev->start_dma, zdev->end_dma,
+ virt_to_phys(zdev->dma_table));
+ if (rc)
+ goto clear_gisa;
+
+out:
+ zdev->kzdev->kvm = kvm;
+
+ spin_lock(&kvm->arch.kzdev_list_lock);
+ list_add_tail(&zdev->kzdev->entry, &kvm->arch.kzdev_list);
+ spin_unlock(&kvm->arch.kzdev_list_lock);
+
+ mutex_unlock(&kvm->lock);
+ return 0;
+
+clear_gisa:
+ zdev->gisa = 0;
+err:
+ if (zdev->kzdev)
+ kvm_s390_pci_dev_release(zdev);
+ mutex_unlock(&kvm->lock);
+ return rc;
+}
+
+static inline int unregister_kvm(struct zpci_dev *zdev)
+{
+ struct kvm *kvm;
+ int rc;
+
+ if (!zdev->kzdev)
+ return -EINVAL;
+
+ kvm = zdev->kzdev->kvm;
+ mutex_lock(&kvm->lock);
+
+ /*
+ * A 0 gisa means interpretation was never enabled, just remove the
+ * device from the list.
+ */
+ if (zdev->gisa == 0)
+ goto out;
+
+ /* Forwarding must be turned off before interpretation */
+ if (zdev->kzdev->fib.fmt0.aibv != 0)
+ kvm_s390_pci_aif_disable(zdev, true);
+
+ /* Remove the host CLP guest designation */
+ zdev->gisa = 0;
+
+ if (zdev_enabled(zdev)) {
+ rc = zpci_disable_device(zdev);
+ if (rc)
+ goto out;
+ }
+
+ rc = zpci_enable_device(zdev);
+ if (rc)
+ goto out;
+
+ /* Re-register the IOMMU that was already created */
+ rc = zpci_register_ioat(zdev, 0, zdev->start_dma, zdev->end_dma,
+ virt_to_phys(zdev->dma_table));
+
+out:
+ spin_lock(&kvm->arch.kzdev_list_lock);
+ list_del(&zdev->kzdev->entry);
+ spin_unlock(&kvm->arch.kzdev_list_lock);
+ kvm_s390_pci_dev_release(zdev);
+
+ mutex_unlock(&kvm->lock);
+
+ return rc;
+}
+
+int kvm_s390_pci_register_kvm(struct zpci_dev *zdev, struct kvm *kvm)
+{
+ if (!zdev)
+ return 0;
+
+ /*
+ * Register device with this KVM (or remove the KVM association if 0).
+ * If interpetation facilities are available, enable them and let
+ * userspace indicate whether or not they will be used (specify SHM bit
+ * to disable).
+ */
+ if (kvm)
+ return register_kvm(zdev, kvm);
+ else
+ return unregister_kvm(zdev);
+}
+EXPORT_SYMBOL_GPL(kvm_s390_pci_register_kvm);
+
+void kvm_s390_pci_init_list(struct kvm *kvm)
+{
+ spin_lock_init(&kvm->arch.kzdev_list_lock);
+ INIT_LIST_HEAD(&kvm->arch.kzdev_list);
+}
+
+void kvm_s390_pci_clear_list(struct kvm *kvm)
+{
+ struct kvm_zdev *tmp, *kzdev;
+ LIST_HEAD(remove);
+
+ spin_lock(&kvm->arch.kzdev_list_lock);
+ list_for_each_entry_safe(kzdev, tmp, &kvm->arch.kzdev_list, entry)
+ list_move_tail(&kzdev->entry, &remove);
+ spin_unlock(&kvm->arch.kzdev_list_lock);
+
+ list_for_each_entry_safe(kzdev, tmp, &remove, entry)
+ unregister_kvm(kzdev->zdev);
+}
+
int kvm_s390_pci_init(void)
{
aift = kzalloc(sizeof(struct zpci_aift), GFP_KERNEL);
diff --git a/arch/s390/kvm/pci.h b/arch/s390/kvm/pci.h
index f567c3189a40..d11662fadb78 100644
--- a/arch/s390/kvm/pci.h
+++ b/arch/s390/kvm/pci.h
@@ -13,6 +13,7 @@
#include <linux/kvm_host.h>
#include <linux/pci.h>
#include <linux/mutex.h>
+#include <linux/kvm.h>
#include <linux/kvm_host.h>
#include <asm/airq.h>
#include <asm/cpu.h>
@@ -21,6 +22,7 @@ struct kvm_zdev {
struct zpci_dev *zdev;
struct kvm *kvm;
struct zpci_fib fib;
+ struct list_head entry;
};

struct zpci_gaite {
@@ -54,6 +56,9 @@ static inline struct kvm *kvm_s390_pci_si_to_kvm(struct zpci_aift *aift,
int kvm_s390_pci_aen_init(u8 nisc);
void kvm_s390_pci_aen_exit(void);

+void kvm_s390_pci_init_list(struct kvm *kvm);
+void kvm_s390_pci_clear_list(struct kvm *kvm);
+
int kvm_s390_pci_init(void);
void kvm_s390_pci_exit(void);

diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
index f0a439c43395..d9b021fb84d5 100644
--- a/arch/s390/pci/pci.c
+++ b/arch/s390/pci/pci.c
@@ -132,6 +132,7 @@ int zpci_register_ioat(struct zpci_dev *zdev, u8 dmaas,
zpci_dbg(3, "reg ioat fid:%x, cc:%d, status:%d\n", zdev->fid, cc, status);
return cc;
}
+EXPORT_SYMBOL_GPL(zpci_register_ioat);

/* Modify PCI: Unregister I/O address translation parameters */
int zpci_unregister_ioat(struct zpci_dev *zdev, u8 dmaas)
@@ -712,6 +713,7 @@ int zpci_enable_device(struct zpci_dev *zdev)
zpci_update_fh(zdev, fh);
return rc;
}
+EXPORT_SYMBOL_GPL(zpci_enable_device);

int zpci_disable_device(struct zpci_dev *zdev)
{
@@ -735,6 +737,7 @@ int zpci_disable_device(struct zpci_dev *zdev)
}
return rc;
}
+EXPORT_SYMBOL_GPL(zpci_disable_device);

/**
* zpci_hot_reset_device - perform a reset of the given zPCI function
--
2.27.0