Re: [PATCH v5 2/5] drm/xe/irq: Separate MSI and MSI-X flows

["Levi, Ilia" <ilia.levi@intel.com>]

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On 02/12/2024 20:59, Piotr Piórkowski wrote:
> Ilia Levi <ilia.levi@intel.com> wrote on czw [2024-lis-28 14:53:42 +0200]:
>> A new flow is added for devices that support MSI-X:
>> - MSI-X vector 0 is used for GuC-to-host interrupt
>> - MSI-X vector 1 (aka default MSI-X) is used for HW engines
>>
>> The default MSI-X will be passed to the HW engines in a subsequent
>> patch.
>>
>> Signed-off-by: Ilia Levi <ilia.levi@intel.com>
>> ---
>>  drivers/gpu/drm/xe/xe_device.c       |   4 +-
>>  drivers/gpu/drm/xe/xe_device.h       |   3 +-
>>  drivers/gpu/drm/xe/xe_device_types.h |   6 +
>>  drivers/gpu/drm/xe/xe_irq.c          | 257 +++++++++++++++++++++++----
>>  drivers/gpu/drm/xe/xe_irq.h          |   3 +
>>  5 files changed, 237 insertions(+), 36 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c
>> index 930bb2750e2e..f1246fa8b5cc 100644
>> --- a/drivers/gpu/drm/xe/xe_device.c
>> +++ b/drivers/gpu/drm/xe/xe_device.c
>> @@ -325,7 +325,9 @@ struct xe_device *xe_device_create(struct pci_dev *pdev,
>>  	xe->info.revid = pdev->revision;
>>  	xe->info.force_execlist = xe_modparam.force_execlist;
>>  
>> -	spin_lock_init(&xe->irq.lock);
>> +	err = xe_irq_init(xe);
>> +	if (err)
>> +		goto err;
>>  
>>  	init_waitqueue_head(&xe->ufence_wq);
>>  
>> diff --git a/drivers/gpu/drm/xe/xe_device.h b/drivers/gpu/drm/xe/xe_device.h
>> index f1fbfe916867..fc3c2af3fb7f 100644
>> --- a/drivers/gpu/drm/xe/xe_device.h
>> +++ b/drivers/gpu/drm/xe/xe_device.h
>> @@ -157,8 +157,7 @@ static inline bool xe_device_has_sriov(struct xe_device *xe)
>>  
>>  static inline bool xe_device_has_msix(struct xe_device *xe)
>>  {
> I still think you should use the name xe_device_use_msix.
>
> We use xe_device_has_* in case, when the capability based on Platform
> version (for example xe_device_has_memirq) based on intel_device_info
> (for example xe_device_has_sriov or xe_device_has_flat_css).
>
> IMO in case you are basing it on a variable that you set yourself in init you should use
> a different name (for example with “uses” instead of “has”)
>
> My motivation is that for me xe_device_has-* is used when it is the capability of a given device
> and we base on the information that intel_device_info or infromation about the platform version
> provides us with.

As we discussed, it is akin to xe_device_has_flat_ccs - where xe->info.has_flat_ccs is set by probe_has_flat_ccs.
xe->irq.msix.nvec is set according to pci_msix_vec_count which reads MSI-X capability from the PCI.

>> -	/* TODO: change this when MSI-X support is fully integrated */
>> -	return false;
>> +	return xe->irq.msix.nvec > 0;
>>  }
>>  
>>  static inline bool xe_device_has_memirq(struct xe_device *xe)
>> diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
>> index 7ee114c17552..ed638067aa26 100644
>> --- a/drivers/gpu/drm/xe/xe_device_types.h
>> +++ b/drivers/gpu/drm/xe/xe_device_types.h
>> @@ -348,6 +348,12 @@ struct xe_device {
>>  
>>  		/** @irq.enabled: interrupts enabled on this device */
>>  		atomic_t enabled;
>> +
>> +		/** @irq.msix: irq info for platforms that support MSI-X */
>> +		struct {
>> +			/** @irq.msix.nvec: number of MSI-X interrupts */
>> +			u16 nvec;
>> +		} msix;
>>  	} irq;
>>  
>>  	/** @ttm: ttm device */
>> diff --git a/drivers/gpu/drm/xe/xe_irq.c b/drivers/gpu/drm/xe/xe_irq.c
>> index 1c509e66694d..b8a0b9bbf24c 100644
>> --- a/drivers/gpu/drm/xe/xe_irq.c
>> +++ b/drivers/gpu/drm/xe/xe_irq.c
>> @@ -10,6 +10,7 @@
>>  #include <drm/drm_managed.h>
>>  
>>  #include "display/xe_display.h"
>> +#include "regs/xe_guc_regs.h"
> I don't see why you are adding this header

GUC_INTR_GUC2HOST is defined there. It was not needed before as it was called by gt_other_irq_handler (the type of the interrupt was read from the registers).
For MSI-X those registers are no longer set - and the only type of interrupt we expect on MSI-X vector 0 is guc-to-host.

>
> Thanks,
> Piotr
>>  #include "regs/xe_irq_regs.h"
>>  #include "xe_device.h"
>>  #include "xe_drv.h"
>> @@ -29,6 +30,11 @@
>>  #define IIR(offset)				XE_REG(offset + 0x8)
>>  #define IER(offset)				XE_REG(offset + 0xc)
>>  
>> +static int xe_irq_msix_init(struct xe_device *xe);
>> +static void xe_irq_msix_free(struct xe_device *xe);
>> +static int xe_irq_msix_request_irqs(struct xe_device *xe);
>> +static void xe_irq_msix_synchronize_irq(struct xe_device *xe);
>> +
>>  static void assert_iir_is_zero(struct xe_mmio *mmio, struct xe_reg reg)
>>  {
>>  	u32 val = xe_mmio_read32(mmio, reg);
>> @@ -572,6 +578,11 @@ static void xe_irq_reset(struct xe_device *xe)
>>  	if (IS_SRIOV_VF(xe))
>>  		return vf_irq_reset(xe);
>>  
>> +	if (xe_device_uses_memirq(xe)) {
>> +		for_each_tile(tile, xe, id)
>> +			xe_memirq_reset(&tile->memirq);
>> +	}
>> +
>>  	for_each_tile(tile, xe, id) {
>>  		if (GRAPHICS_VERx100(xe) >= 1210)
>>  			dg1_irq_reset(tile);
>> @@ -614,6 +625,14 @@ static void xe_irq_postinstall(struct xe_device *xe)
>>  	if (IS_SRIOV_VF(xe))
>>  		return vf_irq_postinstall(xe);
>>  
>> +	if (xe_device_uses_memirq(xe)) {
>> +		struct xe_tile *tile;
>> +		unsigned int id;
>> +
>> +		for_each_tile(tile, xe, id)
>> +			xe_memirq_postinstall(&tile->memirq);
>> +	}
>> +
>>  	xe_display_irq_postinstall(xe, xe_root_mmio_gt(xe));
>>  
>>  	/*
>> @@ -656,60 +675,83 @@ static irq_handler_t xe_irq_handler(struct xe_device *xe)
>>  		return xelp_irq_handler;
>>  }
>>  
>> -static void irq_uninstall(void *arg)
>> +static int xe_irq_msi_request_irqs(struct xe_device *xe)
>> +{
>> +	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
>> +	irq_handler_t irq_handler;
>> +	int irq, err;
>> +
>> +	irq_handler = xe_irq_handler(xe);
>> +	if (!irq_handler) {
>> +		drm_err(&xe->drm, "No supported interrupt handler");
>> +		return -EINVAL;
>> +	}
>> +
>> +	irq = pci_irq_vector(pdev, 0);
>> +	err = request_irq(irq, irq_handler, IRQF_SHARED, DRIVER_NAME, xe);
>> +	if (err < 0) {
>> +		drm_err(&xe->drm, "Failed to request MSI IRQ %d\n", err);
>> +		return err;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static void xe_irq_msi_free(struct xe_device *xe)
>>  {
>> -	struct xe_device *xe = arg;
>>  	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
>>  	int irq;
>>  
>> +	irq = pci_irq_vector(pdev, 0);
>> +	free_irq(irq, xe);
>> +}
>> +
>> +static void irq_uninstall(void *arg)
>> +{
>> +	struct xe_device *xe = arg;
>> +
>>  	if (!atomic_xchg(&xe->irq.enabled, 0))
>>  		return;
>>  
>>  	xe_irq_reset(xe);
>>  
>> -	irq = pci_irq_vector(pdev, 0);
>> -	free_irq(irq, xe);
>> +	if (xe_device_has_msix(xe))
>> +		xe_irq_msix_free(xe);
>> +	else
>> +		xe_irq_msi_free(xe);
>> +}
>> +
>> +int xe_irq_init(struct xe_device *xe)
>> +{
>> +	spin_lock_init(&xe->irq.lock);
>> +
>> +	return xe_irq_msix_init(xe);
>>  }
>>  
>>  int xe_irq_install(struct xe_device *xe)
>>  {
>>  	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
>> -	unsigned int irq_flags = PCI_IRQ_MSIX;
>> -	irq_handler_t irq_handler;
>> -	int err, irq, nvec;
>> -
>> -	irq_handler = xe_irq_handler(xe);
>> -	if (!irq_handler) {
>> -		drm_err(&xe->drm, "No supported interrupt handler");
>> -		return -EINVAL;
>> -	}
>> +	unsigned int irq_flags = PCI_IRQ_MSI;
>> +	int nvec = 1;
>> +	int err;
>>  
>>  	xe_irq_reset(xe);
>>  
>> -	nvec = pci_msix_vec_count(pdev);
>> -	if (nvec <= 0) {
>> -		if (nvec == -EINVAL) {
>> -			/* MSIX capability is not supported in the device, using MSI */
>> -			irq_flags = PCI_IRQ_MSI;
>> -			nvec = 1;
>> -		} else {
>> -			drm_err(&xe->drm, "MSIX: Failed getting count\n");
>> -			return nvec;
>> -		}
>> +	if (xe_device_has_msix(xe)) {
>> +		nvec = xe->irq.msix.nvec;
>> +		irq_flags = PCI_IRQ_MSIX;
>>  	}
>>  
>>  	err = pci_alloc_irq_vectors(pdev, nvec, nvec, irq_flags);
>>  	if (err < 0) {
>> -		drm_err(&xe->drm, "MSI/MSIX: Failed to enable support %d\n", err);
>> +		drm_err(&xe->drm, "Failed to allocate IRQ vectors: %d\n", err);
>>  		return err;
>>  	}
>>  
>> -	irq = pci_irq_vector(pdev, 0);
>> -	err = request_irq(irq, irq_handler, IRQF_SHARED, DRIVER_NAME, xe);
>> -	if (err < 0) {
>> -		drm_err(&xe->drm, "Failed to request MSI/MSIX IRQ %d\n", err);
>> +	err = xe_device_has_msix(xe) ? xe_irq_msix_request_irqs(xe) :
>> +					xe_irq_msi_request_irqs(xe);
>> +	if (err)
>>  		return err;
>> -	}
>>  
>>  	atomic_set(&xe->irq.enabled, 1);
>>  
>> @@ -722,18 +764,28 @@ int xe_irq_install(struct xe_device *xe)
>>  	return 0;
>>  
>>  free_irq_handler:
>> -	free_irq(irq, xe);
>> +	if (xe_device_has_msix(xe))
>> +		xe_irq_msix_free(xe);
>> +	else
>> +		xe_irq_msi_free(xe);
>>  
>>  	return err;
>>  }
>>  
>> -void xe_irq_suspend(struct xe_device *xe)
>> +static void xe_irq_msi_synchronize_irq(struct xe_device *xe)
>>  {
>> -	int irq = to_pci_dev(xe->drm.dev)->irq;
>> +	synchronize_irq(to_pci_dev(xe->drm.dev)->irq);
>> +}
>>  
>> +void xe_irq_suspend(struct xe_device *xe)
>> +{
>>  	atomic_set(&xe->irq.enabled, 0); /* no new irqs */
>>  
>> -	synchronize_irq(irq); /* flush irqs */
>> +	/* flush irqs */
>> +	if (xe_device_has_msix(xe))
>> +		xe_irq_msix_synchronize_irq(xe);
>> +	else
>> +		xe_irq_msi_synchronize_irq(xe);
>>  	xe_irq_reset(xe); /* turn irqs off */
>>  }
>>  
>> @@ -754,3 +806,142 @@ void xe_irq_resume(struct xe_device *xe)
>>  	for_each_gt(gt, xe, id)
>>  		xe_irq_enable_hwe(gt);
>>  }
>> +
>> +/* MSI-X related definitions and functions below. */
>> +
>> +enum xe_irq_msix_static {
>> +	GUC2HOST_MSIX = 0,
>> +	DEFAULT_MSIX = XE_IRQ_DEFAULT_MSIX,
>> +	/* Must be last */
>> +	NUM_OF_STATIC_MSIX,
>> +};
>> +
>> +static int xe_irq_msix_init(struct xe_device *xe)
>> +{
>> +	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
>> +	int nvec = pci_msix_vec_count(pdev);
>> +
>> +	if (nvec == -EINVAL)
>> +		return 0;  /* MSI */
>> +
>> +	if (nvec < 0) {
>> +		drm_err(&xe->drm, "Failed getting MSI-X vectors count: %d\n", nvec);
>> +		return nvec;
>> +	}
>> +
>> +	xe->irq.msix.nvec = nvec;
>> +	return 0;
>> +}
>> +
>> +static irqreturn_t guc2host_irq_handler(int irq, void *arg)
>> +{
>> +	struct xe_device *xe = arg;
>> +	struct xe_tile *tile;
>> +	u8 id;
>> +
>> +	if (!atomic_read(&xe->irq.enabled))
>> +		return IRQ_NONE;
>> +
>> +	for_each_tile(tile, xe, id)
>> +		xe_guc_irq_handler(&tile->primary_gt->uc.guc,
>> +				   GUC_INTR_GUC2HOST);
>> +
>> +	return IRQ_HANDLED;
>> +}
>> +
>> +static irqreturn_t xe_irq_msix_default_hwe_handler(int irq, void *arg)
>> +{
>> +	unsigned int tile_id, gt_id;
>> +	struct xe_device *xe = arg;
>> +	struct xe_memirq *memirq;
>> +	struct xe_hw_engine *hwe;
>> +	enum xe_hw_engine_id id;
>> +	struct xe_tile *tile;
>> +	struct xe_gt *gt;
>> +
>> +	if (!atomic_read(&xe->irq.enabled))
>> +		return IRQ_NONE;
>> +
>> +	for_each_tile(tile, xe, tile_id) {
>> +		memirq = &tile->memirq;
>> +		if (!memirq->bo)
>> +			continue;
>> +
>> +		for_each_gt(gt, xe, gt_id) {
>> +			if (gt->tile != tile)
>> +				continue;
>> +
>> +			for_each_hw_engine(hwe, gt, id)
>> +				xe_memirq_hwe_handler(memirq, hwe);
>> +		}
>> +	}
>> +
>> +	return IRQ_HANDLED;
>> +}
>> +
>> +static int xe_irq_msix_request_irq(struct xe_device *xe, irq_handler_t handler,
>> +				   const char *name, u16 msix)
>> +{
>> +	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
>> +	int ret, irq;
>> +
>> +	irq = pci_irq_vector(pdev, msix);
>> +	if (irq < 0)
>> +		return irq;
>> +
>> +	ret = request_irq(irq, handler, IRQF_SHARED, name, xe);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	return 0;
>> +}
>> +
>> +static void xe_irq_msix_free_irq(struct xe_device *xe, u16 msix)
>> +{
>> +	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
>> +	int irq;
>> +
>> +	irq = pci_irq_vector(pdev, msix);
>> +	if (irq < 0) {
>> +		drm_err(&xe->drm, "MSI-X %u can't be released, there is no matching IRQ\n", msix);
>> +		return;
>> +	}
>> +
>> +	free_irq(irq, xe);
>> +}
>> +
>> +static int xe_irq_msix_request_irqs(struct xe_device *xe)
>> +{
>> +	int err;
>> +
>> +	err = xe_irq_msix_request_irq(xe, guc2host_irq_handler,
>> +				      DRIVER_NAME "-guc2host", GUC2HOST_MSIX);
>> +	if (err) {
>> +		drm_err(&xe->drm, "Failed to request MSI-X IRQ %d: %d\n", GUC2HOST_MSIX, err);
>> +		return err;
>> +	}
>> +
>> +	err = xe_irq_msix_request_irq(xe, xe_irq_msix_default_hwe_handler,
>> +				      DRIVER_NAME "-default-msix", DEFAULT_MSIX);
>> +	if (err) {
>> +		drm_err(&xe->drm, "Failed to request MSI-X IRQ %d: %d\n", DEFAULT_MSIX, err);
>> +		xe_irq_msix_free_irq(xe, GUC2HOST_MSIX);
>> +		return err;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static void xe_irq_msix_free(struct xe_device *xe)
>> +{
>> +	xe_irq_msix_free_irq(xe, GUC2HOST_MSIX);
>> +	xe_irq_msix_free_irq(xe, DEFAULT_MSIX);
>> +}
>> +
>> +static void xe_irq_msix_synchronize_irq(struct xe_device *xe)
>> +{
>> +	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
>> +
>> +	synchronize_irq(pci_irq_vector(pdev, GUC2HOST_MSIX));
>> +	synchronize_irq(pci_irq_vector(pdev, DEFAULT_MSIX));
>> +}
>> diff --git a/drivers/gpu/drm/xe/xe_irq.h b/drivers/gpu/drm/xe/xe_irq.h
>> index 067514e13675..24ff16111b96 100644
>> --- a/drivers/gpu/drm/xe/xe_irq.h
>> +++ b/drivers/gpu/drm/xe/xe_irq.h
>> @@ -6,10 +6,13 @@
>>  #ifndef _XE_IRQ_H_
>>  #define _XE_IRQ_H_
>>  
>> +#define XE_IRQ_DEFAULT_MSIX 1
>> +
>>  struct xe_device;
>>  struct xe_tile;
>>  struct xe_gt;
>>  
>> +int xe_irq_init(struct xe_device *xe);
>>  int xe_irq_install(struct xe_device *xe);
>>  void xe_irq_suspend(struct xe_device *xe);
>>  void xe_irq_resume(struct xe_device *xe);
>> -- 
>> 2.43.2
>>

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