2022-09-20 19:49:18

by Matthew Rosato

Subject: [PATCH] KVM: s390: pci: register pci hooks without interpretation

The kvm registration hooks must be registered even if the facilities
necessary for zPCI interpretation are unavailable, as vfio-pci-zdev will
expect to use the hooks regardless.
This fixes an issue where vfio-pci-zdev will fail its open function
because of a missing kvm_register when running on hardware that does not
support zPCI interpretation.

Fixes: ca922fecda6c ("KVM: s390: pci: Hook to access KVM lowlevel from VFIO")
Signed-off-by: Matthew Rosato <[email protected]>
---
arch/s390/kvm/kvm-s390.c | 4 ++--
arch/s390/kvm/pci.c | 14 +++++++++++---
2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
index e20e126944aa..5c7f5f97ea09 100644
--- a/arch/s390/kvm/kvm-s390.c
+++ b/arch/s390/kvm/kvm-s390.c
@@ -510,7 +510,7 @@ int kvm_arch_init(void *opaque)
goto out;
}

- if (kvm_s390_pci_interp_allowed()) {
+ if (IS_ENABLED(CONFIG_VFIO_PCI_ZDEV_KVM)) {
rc = kvm_s390_pci_init();
if (rc) {
pr_err("Unable to allocate AIFT for PCI\n");
@@ -532,7 +532,7 @@ int kvm_arch_init(void *opaque)
void kvm_arch_exit(void)
{
kvm_s390_gib_destroy();
- if (kvm_s390_pci_interp_allowed())
+ if (IS_ENABLED(CONFIG_VFIO_PCI_ZDEV_KVM))
kvm_s390_pci_exit();
debug_unregister(kvm_s390_dbf);
debug_unregister(kvm_s390_dbf_uv);
diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
index 90aaba80696a..c50c1645c0ae 100644
--- a/arch/s390/kvm/pci.c
+++ b/arch/s390/kvm/pci.c
@@ -672,23 +672,31 @@ int kvm_s390_pci_zpci_op(struct kvm *kvm, struct kvm_s390_zpci_op *args)

int kvm_s390_pci_init(void)
{
+ zpci_kvm_hook.kvm_register = kvm_s390_pci_register_kvm;
+ zpci_kvm_hook.kvm_unregister = kvm_s390_pci_unregister_kvm;
+
+ if (!kvm_s390_pci_interp_allowed())
+ return 0;
+
aift = kzalloc(sizeof(struct zpci_aift), GFP_KERNEL);
if (!aift)
return -ENOMEM;

spin_lock_init(&aift->gait_lock);
mutex_init(&aift->aift_lock);
- zpci_kvm_hook.kvm_register = kvm_s390_pci_register_kvm;
- zpci_kvm_hook.kvm_unregister = kvm_s390_pci_unregister_kvm;

return 0;
}

void kvm_s390_pci_exit(void)
{
- mutex_destroy(&aift->aift_lock);
zpci_kvm_hook.kvm_register = NULL;
zpci_kvm_hook.kvm_unregister = NULL;

+ if (!kvm_s390_pci_interp_allowed())
+ return;
+
+ mutex_destroy(&aift->aift_lock);
+
kfree(aift);
}
--
2.37.3

2022-09-21 12:41:56

by Pierre Morel

Subject: Re: [PATCH] KVM: s390: pci: register pci hooks without interpretation

On 9/20/22 21:30, Matthew Rosato wrote:
> The kvm registration hooks must be registered even if the facilities
> necessary for zPCI interpretation are unavailable, as vfio-pci-zdev will
> expect to use the hooks regardless.
> This fixes an issue where vfio-pci-zdev will fail its open function
> because of a missing kvm_register when running on hardware that does not
> support zPCI interpretation.
>
> Fixes: ca922fecda6c ("KVM: s390: pci: Hook to access KVM lowlevel from VFIO")
> Signed-off-by: Matthew Rosato <[email protected]>

Reviewed-by: Pierre Morel <[email protected]>

> ---
> arch/s390/kvm/kvm-s390.c | 4 ++--
> arch/s390/kvm/pci.c | 14 +++++++++++---
> 2 files changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index e20e126944aa..5c7f5f97ea09 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -510,7 +510,7 @@ int kvm_arch_init(void *opaque)
> goto out;
> }
>
> - if (kvm_s390_pci_interp_allowed()) {
> + if (IS_ENABLED(CONFIG_VFIO_PCI_ZDEV_KVM)) {
> rc = kvm_s390_pci_init();
> if (rc) {
> pr_err("Unable to allocate AIFT for PCI\n");
> @@ -532,7 +532,7 @@ int kvm_arch_init(void *opaque)
> void kvm_arch_exit(void)
> {
> kvm_s390_gib_destroy();
> - if (kvm_s390_pci_interp_allowed())
> + if (IS_ENABLED(CONFIG_VFIO_PCI_ZDEV_KVM))
> kvm_s390_pci_exit();
> debug_unregister(kvm_s390_dbf);
> debug_unregister(kvm_s390_dbf_uv);
> diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
> index 90aaba80696a..c50c1645c0ae 100644
> --- a/arch/s390/kvm/pci.c
> +++ b/arch/s390/kvm/pci.c
> @@ -672,23 +672,31 @@ int kvm_s390_pci_zpci_op(struct kvm *kvm, struct kvm_s390_zpci_op *args)
>
> int kvm_s390_pci_init(void)
> {
> + zpci_kvm_hook.kvm_register = kvm_s390_pci_register_kvm;
> + zpci_kvm_hook.kvm_unregister = kvm_s390_pci_unregister_kvm;
> +
> + if (!kvm_s390_pci_interp_allowed())
> + return 0;
> +
> aift = kzalloc(sizeof(struct zpci_aift), GFP_KERNEL);
> if (!aift)
> return -ENOMEM;
>
> spin_lock_init(&aift->gait_lock);
> mutex_init(&aift->aift_lock);
> - zpci_kvm_hook.kvm_register = kvm_s390_pci_register_kvm;
> - zpci_kvm_hook.kvm_unregister = kvm_s390_pci_unregister_kvm;
>
> return 0;
> }
>
> void kvm_s390_pci_exit(void)
> {
> - mutex_destroy(&aift->aift_lock);
> zpci_kvm_hook.kvm_register = NULL;
> zpci_kvm_hook.kvm_unregister = NULL;
>
> + if (!kvm_s390_pci_interp_allowed())
> + return;
> +
> + mutex_destroy(&aift->aift_lock);
> +
> kfree(aift);
> }

--
Pierre Morel
IBM Lab Boeblingen

2022-09-28 12:21:13

by Claudio Imbrenda

Subject: Re: [PATCH] KVM: s390: pci: register pci hooks without interpretation

On Tue, 20 Sep 2022 15:30:25 -0400
Matthew Rosato <[email protected]> wrote:

> The kvm registration hooks must be registered even if the facilities
> necessary for zPCI interpretation are unavailable, as vfio-pci-zdev will
> expect to use the hooks regardless.
> This fixes an issue where vfio-pci-zdev will fail its open function
> because of a missing kvm_register when running on hardware that does not
> support zPCI interpretation.
>
> Fixes: ca922fecda6c ("KVM: s390: pci: Hook to access KVM lowlevel from VFIO")
> Signed-off-by: Matthew Rosato <[email protected]>

Reviewed-by: Claudio Imbrenda <[email protected]>

> ---
> arch/s390/kvm/kvm-s390.c | 4 ++--
> arch/s390/kvm/pci.c | 14 +++++++++++---
> 2 files changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index e20e126944aa..5c7f5f97ea09 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -510,7 +510,7 @@ int kvm_arch_init(void *opaque)
> goto out;
> }
>
> - if (kvm_s390_pci_interp_allowed()) {
> + if (IS_ENABLED(CONFIG_VFIO_PCI_ZDEV_KVM)) {
> rc = kvm_s390_pci_init();
> if (rc) {
> pr_err("Unable to allocate AIFT for PCI\n");
> @@ -532,7 +532,7 @@ int kvm_arch_init(void *opaque)
> void kvm_arch_exit(void)
> {
> kvm_s390_gib_destroy();
> - if (kvm_s390_pci_interp_allowed())
> + if (IS_ENABLED(CONFIG_VFIO_PCI_ZDEV_KVM))
> kvm_s390_pci_exit();
> debug_unregister(kvm_s390_dbf);
> debug_unregister(kvm_s390_dbf_uv);
> diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c
> index 90aaba80696a..c50c1645c0ae 100644
> --- a/arch/s390/kvm/pci.c
> +++ b/arch/s390/kvm/pci.c
> @@ -672,23 +672,31 @@ int kvm_s390_pci_zpci_op(struct kvm *kvm, struct kvm_s390_zpci_op *args)
>
> int kvm_s390_pci_init(void)
> {
> + zpci_kvm_hook.kvm_register = kvm_s390_pci_register_kvm;
> + zpci_kvm_hook.kvm_unregister = kvm_s390_pci_unregister_kvm;
> +
> + if (!kvm_s390_pci_interp_allowed())
> + return 0;
> +
> aift = kzalloc(sizeof(struct zpci_aift), GFP_KERNEL);
> if (!aift)
> return -ENOMEM;
>
> spin_lock_init(&aift->gait_lock);
> mutex_init(&aift->aift_lock);
> - zpci_kvm_hook.kvm_register = kvm_s390_pci_register_kvm;
> - zpci_kvm_hook.kvm_unregister = kvm_s390_pci_unregister_kvm;
>
> return 0;
> }
>
> void kvm_s390_pci_exit(void)
> {
> - mutex_destroy(&aift->aift_lock);
> zpci_kvm_hook.kvm_register = NULL;
> zpci_kvm_hook.kvm_unregister = NULL;
>
> + if (!kvm_s390_pci_interp_allowed())
> + return;
> +
> + mutex_destroy(&aift->aift_lock);
> +
> kfree(aift);
> }