[dpdk-dev,v3] net/virtio: fix rxq intr config fails using vfio-pci

Message ID 20171109031818.31040-1-zhiyong.yang@intel.com (mailing list archive)
State Superseded, archived
Headers

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/Intel-compilation success Compilation OK

Commit Message

Yang, Zhiyong Nov. 9, 2017, 3:18 a.m. UTC
  When running l3fwd-power to test virtio rxq interrupt using vfio
pci noiommu mode, startup fails. In the function virtio_read_caps,
the code if (flags & PCI_MSIX_ENABLE) intends to double check
if vfio msix is enabled or not. However, it is not enable at that
time. So use_msix is assigned to "0", not "1", which causes the
failure of configuring rxq intr in l3fwd-power.
This patch adds the function "vtpci_msix_detect" to detect the status
of msix when interrupt changes happen.
In the meanwhile, virtio_intr_enable/disable are introduced to wrap
rte_intr_enable/disable to enhance the ability to detect msix. Only
supporting and enabling msix can assign "VIRTIO_MSIX_ENABLED(2)" to
use_msix.

Fixes: cb482cb3a305 ("net/virtio: fix MAC address read")
Signed-off-by: Zhiyong Yang <zhiyong.yang@intel.com>
---

Changes in v3:
Simply the code according to jianfeng's comments.

Changes in v2:
Add the capability to detect msix if virtio intr changes.

 drivers/net/virtio/virtio_ethdev.c | 46 ++++++++++++++++++++++++++++++------
 drivers/net/virtio/virtio_pci.c    | 48 ++++++++++++++++++++++++++++++++++++--
 drivers/net/virtio/virtio_pci.h    |  6 +++++
 3 files changed, 91 insertions(+), 9 deletions(-)
  

Comments

Jianfeng Tan Nov. 9, 2017, 3:47 a.m. UTC | #1
On 11/9/2017 11:18 AM, Zhiyong Yang wrote:
> When running l3fwd-power to test virtio rxq interrupt using vfio
> pci noiommu mode, startup fails. In the function virtio_read_caps,
> the code if (flags & PCI_MSIX_ENABLE) intends to double check
> if vfio msix is enabled or not. However, it is not enable at that
> time. So use_msix is assigned to "0", not "1", which causes the
> failure of configuring rxq intr in l3fwd-power.
> This patch adds the function "vtpci_msix_detect" to detect the status
> of msix when interrupt changes happen.
> In the meanwhile, virtio_intr_enable/disable are introduced to wrap
> rte_intr_enable/disable to enhance the ability to detect msix. Only
> supporting and enabling msix can assign "VIRTIO_MSIX_ENABLED(2)" to
> use_msix.

Above sentence seems not correct. As we can assign VIRTIO_MSIX_NONE, 
VIRTIO_MSIX_DISABLED, VIRTIO_MSIX_ENABLED to use_msix to indicate three 
different msix status.


>
> Fixes: cb482cb3a305 ("net/virtio: fix MAC address read")
> Signed-off-by: Zhiyong Yang <zhiyong.yang@intel.com>
> ---
>
> Changes in v3:
> Simply the code according to jianfeng's comments.
>
> Changes in v2:
> Add the capability to detect msix if virtio intr changes.
>
>   drivers/net/virtio/virtio_ethdev.c | 46 ++++++++++++++++++++++++++++++------
>   drivers/net/virtio/virtio_pci.c    | 48 ++++++++++++++++++++++++++++++++++++--
>   drivers/net/virtio/virtio_pci.h    |  6 +++++
>   3 files changed, 91 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
> index d2576d5e0..87ac2bee6 100644
> --- a/drivers/net/virtio/virtio_ethdev.c
> +++ b/drivers/net/virtio/virtio_ethdev.c
> @@ -97,6 +97,9 @@ static void virtio_mac_addr_remove(struct rte_eth_dev *dev, uint32_t index);
>   static void virtio_mac_addr_set(struct rte_eth_dev *dev,
>   				struct ether_addr *mac_addr);
>   
> +static int virtio_intr_enable(struct rte_eth_dev *dev);
> +static int virtio_intr_disable(struct rte_eth_dev *dev);
> +
>   static int virtio_dev_queue_stats_mapping_set(
>   	struct rte_eth_dev *eth_dev,
>   	uint16_t queue_id,
> @@ -618,7 +621,7 @@ virtio_dev_close(struct rte_eth_dev *dev)
>   		virtio_queues_unbind_intr(dev);
>   
>   	if (intr_conf->lsc || intr_conf->rxq) {
> -		rte_intr_disable(dev->intr_handle);
> +		virtio_intr_disable(dev);
>   		rte_intr_efd_disable(dev->intr_handle);
>   		rte_free(dev->intr_handle->intr_vec);
>   		dev->intr_handle->intr_vec = NULL;
> @@ -1160,6 +1163,34 @@ virtio_vlan_filter_set(struct rte_eth_dev *dev, uint16_t vlan_id, int on)
>   }
>   
>   static int
> +virtio_intr_enable(struct rte_eth_dev *dev)
> +{
> +	struct virtio_hw *hw = dev->data->dev_private;
> +
> +	if (rte_intr_enable(dev->intr_handle) < 0)
> +		return -1;
> +
> +	if (!hw->virtio_user_dev)
> +		hw->use_msix = vtpci_msix_detect(RTE_ETH_DEV_TO_PCI(dev));

Maybe we can check hw->use_msix as an additional check; if it does not 
equal VIRTIO_MSIX_ENABLE, returns -1.

> +
> +	return 0;
> +}
> +
> +static int
> +virtio_intr_disable(struct rte_eth_dev *dev)
> +{
> +	struct virtio_hw *hw = dev->data->dev_private;
> +
> +	if (rte_intr_disable(dev->intr_handle) < 0)
> +		return -1;
> +
> +	if (!hw->virtio_user_dev)
> +		hw->use_msix = vtpci_msix_detect(RTE_ETH_DEV_TO_PCI(dev));
> +
> +	return 0;
> +}
> +
> +static int
>   virtio_negotiate_features(struct virtio_hw *hw, uint64_t req_features)
>   {
>   	uint64_t host_features;
> @@ -1228,7 +1259,7 @@ virtio_interrupt_handler(void *param)
>   	isr = vtpci_isr(hw);
>   	PMD_DRV_LOG(INFO, "interrupt status = %#x", isr);
>   
> -	if (rte_intr_enable(dev->intr_handle) < 0)
> +	if (virtio_intr_enable(dev) < 0)
>   		PMD_DRV_LOG(ERR, "interrupt enable failed");
>   
>   	if (isr & VIRTIO_PCI_ISR_CONFIG) {
> @@ -1348,7 +1379,7 @@ virtio_configure_intr(struct rte_eth_dev *dev)
>   	 * to change the config size from 20 to 24, or VIRTIO_MSI_QUEUE_VECTOR
>   	 * (22) will be ignored.
>   	 */
> -	if (rte_intr_enable(dev->intr_handle) < 0) {
> +	if (virtio_intr_enable(dev) < 0) {
>   		PMD_DRV_LOG(ERR, "interrupt enable failed");
>   		return -1;
>   	}
> @@ -1388,7 +1419,8 @@ virtio_init_device(struct rte_eth_dev *eth_dev, uint64_t req_features)
>   	}
>   
>   	/* If host does not support both status and MSI-X then disable LSC */
> -	if (vtpci_with_feature(hw, VIRTIO_NET_F_STATUS) && hw->use_msix)
> +	if (vtpci_with_feature(hw, VIRTIO_NET_F_STATUS) &&
> +	    hw->use_msix != VIRTIO_MSIX_NONE)
>   		eth_dev->data->dev_flags |= RTE_ETH_DEV_INTR_LSC;
>   	else
>   		eth_dev->data->dev_flags &= ~RTE_ETH_DEV_INTR_LSC;
> @@ -1801,9 +1833,9 @@ virtio_dev_start(struct rte_eth_dev *dev)
>   	 */
>   	if (dev->data->dev_conf.intr_conf.lsc ||
>   	    dev->data->dev_conf.intr_conf.rxq) {
> -		rte_intr_disable(dev->intr_handle);
> +		virtio_intr_disable(dev);
>   
> -		if (rte_intr_enable(dev->intr_handle) < 0) {
> +		if (virtio_intr_enable(dev) < 0) {
>   			PMD_DRV_LOG(ERR, "interrupt enable failed");
>   			return -EIO;
>   		}
> @@ -1912,7 +1944,7 @@ virtio_dev_stop(struct rte_eth_dev *dev)
>   	PMD_INIT_LOG(DEBUG, "stop");
>   
>   	if (intr_conf->lsc || intr_conf->rxq)
> -		rte_intr_disable(dev->intr_handle);
> +		virtio_intr_disable(dev);
>   
>   	hw->started = 0;
>   	memset(&link, 0, sizeof(link));
> diff --git a/drivers/net/virtio/virtio_pci.c b/drivers/net/virtio/virtio_pci.c
> index 55b717c03..10c45228c 100644
> --- a/drivers/net/virtio/virtio_pci.c
> +++ b/drivers/net/virtio/virtio_pci.c
> @@ -57,7 +57,8 @@
>    * The remaining space is defined by each driver as the per-driver
>    * configuration space.
>    */
> -#define VIRTIO_PCI_CONFIG(hw) (((hw)->use_msix) ? 24 : 20)
> +#define VIRTIO_PCI_CONFIG(hw) \
> +		(((hw)->use_msix == VIRTIO_MSIX_ENABLED) ? 24 : 20)
>   
>   static inline int
>   check_vq_phys_addr_ok(struct virtqueue *vq)
> @@ -617,7 +618,9 @@ virtio_read_caps(struct rte_pci_device *dev, struct virtio_hw *hw)
>   			uint16_t flags = ((uint16_t *)&cap)[1];
>   
>   			if (flags & PCI_MSIX_ENABLE)
> -				hw->use_msix = 1;
> +				hw->use_msix = VIRTIO_MSIX_ENABLED;
> +			else
> +				hw->use_msix = VIRTIO_MSIX_DISABLED;
>   		}
>   
>   		if (cap.cap_vndr != PCI_CAP_ID_VNDR) {
> @@ -710,3 +713,44 @@ vtpci_init(struct rte_pci_device *dev, struct virtio_hw *hw)
>   
>   	return 0;
>   }
> +
> +/* Return 0 (VIRTIO_MSIX_NONE)
> + * Return 1 (VIRTIO_MSIX_DISABLED)
> + * Return 2 (VIRTIO_MSIX_ENABLED)
> + */
> +
> +uint8_t
> +vtpci_msix_detect(struct rte_pci_device *dev)
> +{
> +	uint8_t pos;
> +	struct virtio_pci_cap cap;
> +	int ret;
> +
> +	ret = rte_pci_read_config(dev, &pos, 1, PCI_CAPABILITY_LIST);
> +	if (ret < 0) {
> +		PMD_INIT_LOG(DEBUG, "failed to read pci capability list");
> +		return VIRTIO_MSIX_NONE;
> +	}
> +
> +	while (pos) {
> +		ret = rte_pci_read_config(dev, &cap, sizeof(cap), pos);
> +		if (ret < 0) {
> +			PMD_INIT_LOG(ERR,
> +				"failed to read pci cap at pos: %x", pos);
> +			break;
> +		}
> +
> +		if (cap.cap_vndr == PCI_CAP_ID_MSIX) {
> +			uint16_t flags = ((uint16_t *)&cap)[1];
> +
> +			if (flags & PCI_MSIX_ENABLE)
> +				return VIRTIO_MSIX_ENABLED;
> +			else
> +				return VIRTIO_MSIX_DISABLED;
> +		}
> +
> +		pos = cap.cap_next;
> +	}
> +
> +	return VIRTIO_MSIX_NONE;
> +}
> diff --git a/drivers/net/virtio/virtio_pci.h b/drivers/net/virtio/virtio_pci.h
> index 36d452c06..600e106eb 100644
> --- a/drivers/net/virtio/virtio_pci.h
> +++ b/drivers/net/virtio/virtio_pci.h
> @@ -314,6 +314,10 @@ struct virtio_net_config {
>   /* The alignment to use between consumer and producer parts of vring. */
>   #define VIRTIO_PCI_VRING_ALIGN 4096
>   
> +#define VIRTIO_MSIX_NONE 0
> +#define VIRTIO_MSIX_DISABLED 1
> +#define VIRTIO_MSIX_ENABLED 2
> +
>   static inline int
>   vtpci_with_feature(struct virtio_hw *hw, uint64_t bit)
>   {
> @@ -339,6 +343,8 @@ void vtpci_read_dev_config(struct virtio_hw *, size_t, void *, int);
>   
>   uint8_t vtpci_isr(struct virtio_hw *);
>   
> +uint8_t vtpci_msix_detect(struct rte_pci_device *dev);
> +
>   extern const struct virtio_pci_ops legacy_ops;
>   extern const struct virtio_pci_ops modern_ops;
>   extern const struct virtio_pci_ops virtio_user_ops;
  
Yang, Zhiyong Nov. 9, 2017, 4:01 a.m. UTC | #2
> -----Original Message-----
> From: Tan, Jianfeng
> Sent: Thursday, November 9, 2017 11:47 AM
> To: Yang, Zhiyong <zhiyong.yang@intel.com>; dev@dpdk.org
> Cc: yliu@fridaylinux.org
> Subject: Re: [PATCH v3] net/virtio: fix rxq intr config fails using vfio-pci
> 
> 
> 
> On 11/9/2017 11:18 AM, Zhiyong Yang wrote:
> > When running l3fwd-power to test virtio rxq interrupt using vfio pci
> > noiommu mode, startup fails. In the function virtio_read_caps, the
> > code if (flags & PCI_MSIX_ENABLE) intends to double check if vfio msix
> > is enabled or not. However, it is not enable at that time. So use_msix
> > is assigned to "0", not "1", which causes the failure of configuring
> > rxq intr in l3fwd-power.
> > This patch adds the function "vtpci_msix_detect" to detect the status
> > of msix when interrupt changes happen.
> > In the meanwhile, virtio_intr_enable/disable are introduced to wrap
> > rte_intr_enable/disable to enhance the ability to detect msix. Only
> > supporting and enabling msix can assign "VIRTIO_MSIX_ENABLED(2)" to
> > use_msix.
> 
> Above sentence seems not correct. As we can assign VIRTIO_MSIX_NONE,
> VIRTIO_MSIX_DISABLED, VIRTIO_MSIX_ENABLED to use_msix to indicate three
> different msix status.
> 

Right, I just want to say, supporting and enabling msix are true, use_misx can be assigned to 2.

> 
> >
> > Fixes: cb482cb3a305 ("net/virtio: fix MAC address read")
> > Signed-off-by: Zhiyong Yang <zhiyong.yang@intel.com>
> > ---
> >
> > Changes in v3:
> > Simply the code according to jianfeng's comments.
> >
> > Changes in v2:
> > Add the capability to detect msix if virtio intr changes.
> >
> >   drivers/net/virtio/virtio_ethdev.c | 46 ++++++++++++++++++++++++++++++--
> ----
> >   drivers/net/virtio/virtio_pci.c    | 48
> ++++++++++++++++++++++++++++++++++++--
> >   drivers/net/virtio/virtio_pci.h    |  6 +++++
> >   3 files changed, 91 insertions(+), 9 deletions(-)
> >
> > diff --git a/drivers/net/virtio/virtio_ethdev.c
> > b/drivers/net/virtio/virtio_ethdev.c
> > index d2576d5e0..87ac2bee6 100644
> > --- a/drivers/net/virtio/virtio_ethdev.c
> > +++ b/drivers/net/virtio/virtio_ethdev.c
> > @@ -97,6 +97,9 @@ static void virtio_mac_addr_remove(struct rte_eth_dev
> *dev, uint32_t index);
> >   static void virtio_mac_addr_set(struct rte_eth_dev *dev,
> >   				struct ether_addr *mac_addr);
> >
> > +static int virtio_intr_enable(struct rte_eth_dev *dev); static int
> > +virtio_intr_disable(struct rte_eth_dev *dev);
> > +
> >   static int virtio_dev_queue_stats_mapping_set(
> >   	struct rte_eth_dev *eth_dev,
> >   	uint16_t queue_id,
> > @@ -618,7 +621,7 @@ virtio_dev_close(struct rte_eth_dev *dev)
> >   		virtio_queues_unbind_intr(dev);
> >
> >   	if (intr_conf->lsc || intr_conf->rxq) {
> > -		rte_intr_disable(dev->intr_handle);
> > +		virtio_intr_disable(dev);
> >   		rte_intr_efd_disable(dev->intr_handle);
> >   		rte_free(dev->intr_handle->intr_vec);
> >   		dev->intr_handle->intr_vec = NULL; @@ -1160,6 +1163,34 @@
> > virtio_vlan_filter_set(struct rte_eth_dev *dev, uint16_t vlan_id, int on)
> >   }
> >
> >   static int
> > +virtio_intr_enable(struct rte_eth_dev *dev) {
> > +	struct virtio_hw *hw = dev->data->dev_private;
> > +
> > +	if (rte_intr_enable(dev->intr_handle) < 0)
> > +		return -1;
> > +
> > +	if (!hw->virtio_user_dev)
> > +		hw->use_msix = vtpci_msix_detect(RTE_ETH_DEV_TO_PCI(dev));
> 
> Maybe we can check hw->use_msix as an additional check; if it does not equal
> VIRTIO_MSIX_ENABLE, returns -1.
>  
From my understanding, it is unnecessary. 
Functionality of virtio_intr_enable  should be generic.
Igb_uio or other can use it. it should be no harm to others.
 we add msix detect here in order to just get use_msix status. 

Thanks
Zhiyong
  
Jianfeng Tan Nov. 9, 2017, 4:40 a.m. UTC | #3
On 11/9/2017 12:01 PM, Yang, Zhiyong wrote:

>>>    static int
>>> +virtio_intr_enable(struct rte_eth_dev *dev) {
>>> +	struct virtio_hw *hw = dev->data->dev_private;
>>> +
>>> +	if (rte_intr_enable(dev->intr_handle) < 0)
>>> +		return -1;
>>> +
>>> +	if (!hw->virtio_user_dev)
>>> +		hw->use_msix = vtpci_msix_detect(RTE_ETH_DEV_TO_PCI(dev));
>> Maybe we can check hw->use_msix as an additional check; if it does not equal
>> VIRTIO_MSIX_ENABLE, returns -1.
>>   
>  From my understanding, it is unnecessary.
> Functionality of virtio_intr_enable  should be generic.
> Igb_uio or other can use it. it should be no harm to others.
>   we add msix detect here in order to just get use_msix status.

Fair enough.

>
> Thanks
> Zhiyong
  

Patch

diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
index d2576d5e0..87ac2bee6 100644
--- a/drivers/net/virtio/virtio_ethdev.c
+++ b/drivers/net/virtio/virtio_ethdev.c
@@ -97,6 +97,9 @@  static void virtio_mac_addr_remove(struct rte_eth_dev *dev, uint32_t index);
 static void virtio_mac_addr_set(struct rte_eth_dev *dev,
 				struct ether_addr *mac_addr);
 
+static int virtio_intr_enable(struct rte_eth_dev *dev);
+static int virtio_intr_disable(struct rte_eth_dev *dev);
+
 static int virtio_dev_queue_stats_mapping_set(
 	struct rte_eth_dev *eth_dev,
 	uint16_t queue_id,
@@ -618,7 +621,7 @@  virtio_dev_close(struct rte_eth_dev *dev)
 		virtio_queues_unbind_intr(dev);
 
 	if (intr_conf->lsc || intr_conf->rxq) {
-		rte_intr_disable(dev->intr_handle);
+		virtio_intr_disable(dev);
 		rte_intr_efd_disable(dev->intr_handle);
 		rte_free(dev->intr_handle->intr_vec);
 		dev->intr_handle->intr_vec = NULL;
@@ -1160,6 +1163,34 @@  virtio_vlan_filter_set(struct rte_eth_dev *dev, uint16_t vlan_id, int on)
 }
 
 static int
+virtio_intr_enable(struct rte_eth_dev *dev)
+{
+	struct virtio_hw *hw = dev->data->dev_private;
+
+	if (rte_intr_enable(dev->intr_handle) < 0)
+		return -1;
+
+	if (!hw->virtio_user_dev)
+		hw->use_msix = vtpci_msix_detect(RTE_ETH_DEV_TO_PCI(dev));
+
+	return 0;
+}
+
+static int
+virtio_intr_disable(struct rte_eth_dev *dev)
+{
+	struct virtio_hw *hw = dev->data->dev_private;
+
+	if (rte_intr_disable(dev->intr_handle) < 0)
+		return -1;
+
+	if (!hw->virtio_user_dev)
+		hw->use_msix = vtpci_msix_detect(RTE_ETH_DEV_TO_PCI(dev));
+
+	return 0;
+}
+
+static int
 virtio_negotiate_features(struct virtio_hw *hw, uint64_t req_features)
 {
 	uint64_t host_features;
@@ -1228,7 +1259,7 @@  virtio_interrupt_handler(void *param)
 	isr = vtpci_isr(hw);
 	PMD_DRV_LOG(INFO, "interrupt status = %#x", isr);
 
-	if (rte_intr_enable(dev->intr_handle) < 0)
+	if (virtio_intr_enable(dev) < 0)
 		PMD_DRV_LOG(ERR, "interrupt enable failed");
 
 	if (isr & VIRTIO_PCI_ISR_CONFIG) {
@@ -1348,7 +1379,7 @@  virtio_configure_intr(struct rte_eth_dev *dev)
 	 * to change the config size from 20 to 24, or VIRTIO_MSI_QUEUE_VECTOR
 	 * (22) will be ignored.
 	 */
-	if (rte_intr_enable(dev->intr_handle) < 0) {
+	if (virtio_intr_enable(dev) < 0) {
 		PMD_DRV_LOG(ERR, "interrupt enable failed");
 		return -1;
 	}
@@ -1388,7 +1419,8 @@  virtio_init_device(struct rte_eth_dev *eth_dev, uint64_t req_features)
 	}
 
 	/* If host does not support both status and MSI-X then disable LSC */
-	if (vtpci_with_feature(hw, VIRTIO_NET_F_STATUS) && hw->use_msix)
+	if (vtpci_with_feature(hw, VIRTIO_NET_F_STATUS) &&
+	    hw->use_msix != VIRTIO_MSIX_NONE)
 		eth_dev->data->dev_flags |= RTE_ETH_DEV_INTR_LSC;
 	else
 		eth_dev->data->dev_flags &= ~RTE_ETH_DEV_INTR_LSC;
@@ -1801,9 +1833,9 @@  virtio_dev_start(struct rte_eth_dev *dev)
 	 */
 	if (dev->data->dev_conf.intr_conf.lsc ||
 	    dev->data->dev_conf.intr_conf.rxq) {
-		rte_intr_disable(dev->intr_handle);
+		virtio_intr_disable(dev);
 
-		if (rte_intr_enable(dev->intr_handle) < 0) {
+		if (virtio_intr_enable(dev) < 0) {
 			PMD_DRV_LOG(ERR, "interrupt enable failed");
 			return -EIO;
 		}
@@ -1912,7 +1944,7 @@  virtio_dev_stop(struct rte_eth_dev *dev)
 	PMD_INIT_LOG(DEBUG, "stop");
 
 	if (intr_conf->lsc || intr_conf->rxq)
-		rte_intr_disable(dev->intr_handle);
+		virtio_intr_disable(dev);
 
 	hw->started = 0;
 	memset(&link, 0, sizeof(link));
diff --git a/drivers/net/virtio/virtio_pci.c b/drivers/net/virtio/virtio_pci.c
index 55b717c03..10c45228c 100644
--- a/drivers/net/virtio/virtio_pci.c
+++ b/drivers/net/virtio/virtio_pci.c
@@ -57,7 +57,8 @@ 
  * The remaining space is defined by each driver as the per-driver
  * configuration space.
  */
-#define VIRTIO_PCI_CONFIG(hw) (((hw)->use_msix) ? 24 : 20)
+#define VIRTIO_PCI_CONFIG(hw) \
+		(((hw)->use_msix == VIRTIO_MSIX_ENABLED) ? 24 : 20)
 
 static inline int
 check_vq_phys_addr_ok(struct virtqueue *vq)
@@ -617,7 +618,9 @@  virtio_read_caps(struct rte_pci_device *dev, struct virtio_hw *hw)
 			uint16_t flags = ((uint16_t *)&cap)[1];
 
 			if (flags & PCI_MSIX_ENABLE)
-				hw->use_msix = 1;
+				hw->use_msix = VIRTIO_MSIX_ENABLED;
+			else
+				hw->use_msix = VIRTIO_MSIX_DISABLED;
 		}
 
 		if (cap.cap_vndr != PCI_CAP_ID_VNDR) {
@@ -710,3 +713,44 @@  vtpci_init(struct rte_pci_device *dev, struct virtio_hw *hw)
 
 	return 0;
 }
+
+/* Return 0 (VIRTIO_MSIX_NONE)
+ * Return 1 (VIRTIO_MSIX_DISABLED)
+ * Return 2 (VIRTIO_MSIX_ENABLED)
+ */
+
+uint8_t
+vtpci_msix_detect(struct rte_pci_device *dev)
+{
+	uint8_t pos;
+	struct virtio_pci_cap cap;
+	int ret;
+
+	ret = rte_pci_read_config(dev, &pos, 1, PCI_CAPABILITY_LIST);
+	if (ret < 0) {
+		PMD_INIT_LOG(DEBUG, "failed to read pci capability list");
+		return VIRTIO_MSIX_NONE;
+	}
+
+	while (pos) {
+		ret = rte_pci_read_config(dev, &cap, sizeof(cap), pos);
+		if (ret < 0) {
+			PMD_INIT_LOG(ERR,
+				"failed to read pci cap at pos: %x", pos);
+			break;
+		}
+
+		if (cap.cap_vndr == PCI_CAP_ID_MSIX) {
+			uint16_t flags = ((uint16_t *)&cap)[1];
+
+			if (flags & PCI_MSIX_ENABLE)
+				return VIRTIO_MSIX_ENABLED;
+			else
+				return VIRTIO_MSIX_DISABLED;
+		}
+
+		pos = cap.cap_next;
+	}
+
+	return VIRTIO_MSIX_NONE;
+}
diff --git a/drivers/net/virtio/virtio_pci.h b/drivers/net/virtio/virtio_pci.h
index 36d452c06..600e106eb 100644
--- a/drivers/net/virtio/virtio_pci.h
+++ b/drivers/net/virtio/virtio_pci.h
@@ -314,6 +314,10 @@  struct virtio_net_config {
 /* The alignment to use between consumer and producer parts of vring. */
 #define VIRTIO_PCI_VRING_ALIGN 4096
 
+#define VIRTIO_MSIX_NONE 0
+#define VIRTIO_MSIX_DISABLED 1
+#define VIRTIO_MSIX_ENABLED 2
+
 static inline int
 vtpci_with_feature(struct virtio_hw *hw, uint64_t bit)
 {
@@ -339,6 +343,8 @@  void vtpci_read_dev_config(struct virtio_hw *, size_t, void *, int);
 
 uint8_t vtpci_isr(struct virtio_hw *);
 
+uint8_t vtpci_msix_detect(struct rte_pci_device *dev);
+
 extern const struct virtio_pci_ops legacy_ops;
 extern const struct virtio_pci_ops modern_ops;
 extern const struct virtio_pci_ops virtio_user_ops;