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From:   Reinette Chatre <reinette.chatre@intel.com>
To:     jgg@nvidia.com, yishaih@nvidia.com,
        shameerali.kolothum.thodi@huawei.com, kevin.tian@intel.com,
        alex.williamson@redhat.com
Cc:     kvm@vger.kernel.org, dave.jiang@intel.com, jing2.liu@intel.com,
        ashok.raj@intel.com, fenghua.yu@intel.com,
        tom.zanussi@linux.intel.com, reinette.chatre@intel.com,
        linux-kernel@vger.kernel.org, patches@lists.linux.dev
Subject: [RFC PATCH V3 04/26] vfio/pci: Make core interrupt callbacks accessible to all virtual devices
Date:   Fri, 27 Oct 2023 10:00:36 -0700
Message-Id: <52141bbf2a7e7c4d0a9ce74e2f652b8f4e3211fd.1698422237.git.reinette.chatre@intel.com>
In-Reply-To: <cover.1698422237.git.reinette.chatre@intel.com>
References: <cover.1698422237.git.reinette.chatre@intel.com>
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The functions handling actions on interrupts for a virtual PCI device
triggered by VFIO_DEVICE_SET_IRQS ioctl() expect to act on a passthrough
PCI device represented by a struct vfio_pci_core_device.

A virtual device can support MSI-X while not being a passthrough PCI
device and thus not be represented by a struct vfio_pci_core_device.

To support MSI-X in virtual devices it needs to be possible for
their drivers to interact with the MSI-X interrupt management and
thus the interrupt management should not require struct
vfio_pci_core_device.

Introduce struct vfio_pci_intr_ctx that will contain a virtual device's
interrupt context to be managed by an interrupt management backend.
The first supported backend is the existing PCI device interrupt
management. Modify the core VFIO PCI interrupt management functions
to expect this structure. As a backend managing interrupts of
passthrough PCI devices the existing VFIO PCI functions continue to
operate on an actual PCI device represented by
struct vfio_pci_core_device that is provided via a private pointer.

More members will be added to struct vfio_pci_intr_ctx as members
unique to interrupt context are transitioned from struct
vfio_pci_core_device.

Signed-off-by: Reinette Chatre <reinette.chatre@intel.com>
---
Changes since RFC V2:
- Improve changelog and comments.

 drivers/vfio/pci/vfio_pci_core.c  |  7 ++++---
 drivers/vfio/pci/vfio_pci_intrs.c | 29 ++++++++++++++++++++---------
 drivers/vfio/pci/vfio_pci_priv.h  |  2 +-
 include/linux/vfio_pci_core.h     |  9 +++++++++
 4 files changed, 34 insertions(+), 13 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index 1929103ee59a..bb8181444c41 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -594,7 +594,7 @@ void vfio_pci_core_disable(struct vfio_pci_core_device *vdev)
 	/* Stop the device from further DMA */
 	pci_clear_master(pdev);
 
-	vfio_pci_set_irqs_ioctl(vdev, VFIO_IRQ_SET_DATA_NONE |
+	vfio_pci_set_irqs_ioctl(&vdev->intr_ctx, VFIO_IRQ_SET_DATA_NONE |
 				VFIO_IRQ_SET_ACTION_TRIGGER,
 				vdev->irq_type, 0, 0, NULL);
 
@@ -1216,8 +1216,8 @@ static int vfio_pci_ioctl_set_irqs(struct vfio_pci_core_device *vdev,
 
 	mutex_lock(&vdev->igate);
 
-	ret = vfio_pci_set_irqs_ioctl(vdev, hdr.flags, hdr.index, hdr.start,
-				      hdr.count, data);
+	ret = vfio_pci_set_irqs_ioctl(&vdev->intr_ctx, hdr.flags, hdr.index,
+				      hdr.start, hdr.count, data);
 
 	mutex_unlock(&vdev->igate);
 	kfree(data);
@@ -2166,6 +2166,7 @@ int vfio_pci_core_init_dev(struct vfio_device *core_vdev)
 	INIT_LIST_HEAD(&vdev->sriov_pfs_item);
 	init_rwsem(&vdev->memory_lock);
 	xa_init(&vdev->ctx);
+	vdev->intr_ctx.priv = vdev;
 
 	return 0;
 }
diff --git a/drivers/vfio/pci/vfio_pci_intrs.c b/drivers/vfio/pci/vfio_pci_intrs.c
index 9f4f3ab48f87..af1053873eaa 100644
--- a/drivers/vfio/pci/vfio_pci_intrs.c
+++ b/drivers/vfio/pci/vfio_pci_intrs.c
@@ -553,11 +553,13 @@ static void vfio_msi_disable(struct vfio_pci_core_device *vdev, bool msix)
 /*
  * IOCTL support
  */
-static int vfio_pci_set_intx_unmask(struct vfio_pci_core_device *vdev,
+static int vfio_pci_set_intx_unmask(struct vfio_pci_intr_ctx *intr_ctx,
 				    unsigned int index, unsigned int start,
 				    unsigned int count, uint32_t flags,
 				    void *data)
 {
+	struct vfio_pci_core_device *vdev = intr_ctx->priv;
+
 	if (!is_intx(vdev) || start != 0 || count != 1)
 		return -EINVAL;
 
@@ -585,10 +587,12 @@ static int vfio_pci_set_intx_unmask(struct vfio_pci_core_device *vdev,
 	return 0;
 }
 
-static int vfio_pci_set_intx_mask(struct vfio_pci_core_device *vdev,
+static int vfio_pci_set_intx_mask(struct vfio_pci_intr_ctx *intr_ctx,
 				  unsigned int index, unsigned int start,
 				  unsigned int count, uint32_t flags, void *data)
 {
+	struct vfio_pci_core_device *vdev = intr_ctx->priv;
+
 	if (!is_intx(vdev) || start != 0 || count != 1)
 		return -EINVAL;
 
@@ -605,11 +609,13 @@ static int vfio_pci_set_intx_mask(struct vfio_pci_core_device *vdev,
 	return 0;
 }
 
-static int vfio_pci_set_intx_trigger(struct vfio_pci_core_device *vdev,
+static int vfio_pci_set_intx_trigger(struct vfio_pci_intr_ctx *intr_ctx,
 				     unsigned int index, unsigned int start,
 				     unsigned int count, uint32_t flags,
 				     void *data)
 {
+	struct vfio_pci_core_device *vdev = intr_ctx->priv;
+
 	if (is_intx(vdev) && !count && (flags & VFIO_IRQ_SET_DATA_NONE)) {
 		vfio_intx_disable(vdev);
 		return 0;
@@ -649,11 +655,12 @@ static int vfio_pci_set_intx_trigger(struct vfio_pci_core_device *vdev,
 	return 0;
 }
 
-static int vfio_pci_set_msi_trigger(struct vfio_pci_core_device *vdev,
+static int vfio_pci_set_msi_trigger(struct vfio_pci_intr_ctx *intr_ctx,
 				    unsigned int index, unsigned int start,
 				    unsigned int count, uint32_t flags,
 				    void *data)
 {
+	struct vfio_pci_core_device *vdev = intr_ctx->priv;
 	struct vfio_pci_irq_ctx *ctx;
 	unsigned int i;
 	bool msix = (index == VFIO_PCI_MSIX_IRQ_INDEX) ? true : false;
@@ -758,11 +765,13 @@ static int vfio_pci_set_ctx_trigger_single(struct eventfd_ctx **ctx,
 	return -EINVAL;
 }
 
-static int vfio_pci_set_err_trigger(struct vfio_pci_core_device *vdev,
+static int vfio_pci_set_err_trigger(struct vfio_pci_intr_ctx *intr_ctx,
 				    unsigned int index, unsigned int start,
 				    unsigned int count, uint32_t flags,
 				    void *data)
 {
+	struct vfio_pci_core_device *vdev = intr_ctx->priv;
+
 	if (!pci_is_pcie(vdev->pdev))
 		return -ENOTTY;
 
@@ -773,11 +782,13 @@ static int vfio_pci_set_err_trigger(struct vfio_pci_core_device *vdev,
 					       count, flags, data);
 }
 
-static int vfio_pci_set_req_trigger(struct vfio_pci_core_device *vdev,
+static int vfio_pci_set_req_trigger(struct vfio_pci_intr_ctx *intr_ctx,
 				    unsigned int index, unsigned int start,
 				    unsigned int count, uint32_t flags,
 				    void *data)
 {
+	struct vfio_pci_core_device *vdev = intr_ctx->priv;
+
 	if (index != VFIO_PCI_REQ_IRQ_INDEX || start != 0 || count > 1)
 		return -EINVAL;
 
@@ -785,11 +796,11 @@ static int vfio_pci_set_req_trigger(struct vfio_pci_core_device *vdev,
 					       count, flags, data);
 }
 
-int vfio_pci_set_irqs_ioctl(struct vfio_pci_core_device *vdev, uint32_t flags,
+int vfio_pci_set_irqs_ioctl(struct vfio_pci_intr_ctx *intr_ctx, uint32_t flags,
 			    unsigned int index, unsigned int start,
 			    unsigned int count, void *data)
 {
-	int (*func)(struct vfio_pci_core_device *vdev, unsigned int index,
+	int (*func)(struct vfio_pci_intr_ctx *intr_ctx, unsigned int index,
 		    unsigned int start, unsigned int count, uint32_t flags,
 		    void *data) = NULL;
 
@@ -838,5 +849,5 @@ int vfio_pci_set_irqs_ioctl(struct vfio_pci_core_device *vdev, uint32_t flags,
 	if (!func)
 		return -ENOTTY;
 
-	return func(vdev, index, start, count, flags, data);
+	return func(intr_ctx, index, start, count, flags, data);
 }
diff --git a/drivers/vfio/pci/vfio_pci_priv.h b/drivers/vfio/pci/vfio_pci_priv.h
index 5e4fa69aee16..6dddcfe7ab19 100644
--- a/drivers/vfio/pci/vfio_pci_priv.h
+++ b/drivers/vfio/pci/vfio_pci_priv.h
@@ -26,7 +26,7 @@ struct vfio_pci_ioeventfd {
 bool vfio_pci_intx_mask(struct vfio_pci_core_device *vdev);
 void vfio_pci_intx_unmask(struct vfio_pci_core_device *vdev);
 
-int vfio_pci_set_irqs_ioctl(struct vfio_pci_core_device *vdev, uint32_t flags,
+int vfio_pci_set_irqs_ioctl(struct vfio_pci_intr_ctx *intr_ctx, uint32_t flags,
 			    unsigned index, unsigned start, unsigned count,
 			    void *data);
 
diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h
index 562e8754869d..38355a4817fd 100644
--- a/include/linux/vfio_pci_core.h
+++ b/include/linux/vfio_pci_core.h
@@ -49,6 +49,14 @@ struct vfio_pci_region {
 	u32				flags;
 };
 
+/*
+ * Interrupt context of virtual PCI device
+ * @priv:		Private data of interrupt management backend
+ */
+struct vfio_pci_intr_ctx {
+	void				*priv;
+};
+
 struct vfio_pci_core_device {
 	struct vfio_device	vdev;
 	struct pci_dev		*pdev;
@@ -96,6 +104,7 @@ struct vfio_pci_core_device {
 	struct mutex		vma_lock;
 	struct list_head	vma_list;
 	struct rw_semaphore	memory_lock;
+	struct vfio_pci_intr_ctx	intr_ctx;
 };
 
 /* Will be exported for vfio pci drivers usage */
-- 
2.34.1