WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-devel

[Xen-devel] Re: [PATCH] xen: fix MSI setup and teardown for PV on HVM gu

To: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Subject: [Xen-devel] Re: [PATCH] xen: fix MSI setup and teardown for PV on HVM guests
From: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Date: Mon, 29 Nov 2010 12:03:51 -0500
Cc: Jeremy Fitzhardinge <Jeremy.Fitzhardinge@xxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx
Delivery-date: Mon, 29 Nov 2010 09:05:18 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <alpine.DEB.2.00.1011251904370.2373@kaball-desktop>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <alpine.DEB.2.00.1011251904370.2373@kaball-desktop>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mutt/1.5.20 (2009-06-14)
On Fri, Nov 26, 2010 at 02:59:10PM +0000, Stefano Stabellini wrote:
> xen: fix MSI setup and teardown for PV on HVM guests
> 
> When remapping MSIs into pirqs for PV on HVM guests, qemu is responsible
> for doing the actual mapping and unmapping.

Is this QEMU version dependent? 
> We only give qemu the desired pirq number when we ask to do the mapping
> the first time, after that we should be reading back the pirq number
> from qemu every time we want to re-enable the MSI.

What about IRQ migration from CPU to CPU?
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> 
> diff --git a/arch/x86/pci/xen.c b/arch/x86/pci/xen.c
> index d7b5109..ff81d67 100644
> --- a/arch/x86/pci/xen.c
> +++ b/arch/x86/pci/xen.c
> @@ -98,8 +98,26 @@ static int xen_hvm_setup_msi_irqs(struct pci_dev *dev, int 
> nvec, int type)
>       struct msi_msg msg;
>  
>       list_for_each_entry(msidesc, &dev->msi_list, list) {
> +             __read_msi_msg(msidesc, &msg);
> +             pirq = MSI_ADDR_EXT_DEST_ID(msg.address_hi) |
> +                     ((msg.address_lo >> MSI_ADDR_DEST_ID_SHIFT) & 0xff);
> +             if (xen_irq_from_pirq(pirq) >= 0 &&
> +                     msg.data == (MSI_DATA_TRIGGER_EDGE |
> +                                          MSI_DATA_LEVEL_ASSERT |
> +                                              (3 << 8) |
> +                                              MSI_DATA_VECTOR(0))) {

A similar construct is used in xen_msi_compose_msg function. Could you
make this an #define?
> +                     xen_allocate_pirq_msi((type == PCI_CAP_ID_MSIX) ?
> +                                     "msi-x" : "msi", &irq, &pirq, 
> XEN_ALLOC_IRQ);
> +                     if (irq < 0 || pirq < 0)

The pirq value won't be touched at all, since you are passing in XEN_ALLOC_IRQ.
Is there any sense in checking the pirq value here?

> +                             goto error;
> +                     ret = set_irq_msi(irq, msidesc);
> +                     if (ret < 0)
> +                             goto error_while;
> +                     printk(KERN_DEBUG "xen: msi already setup: pirq=%d\n", 
> pirq);

While that is technically correct, would it make sense to add a comment
about setting the IRQ value since the printk "xen: msi-->irq=%d" is not going
to be reached?
> +                     return 0;
> +             }
>               xen_allocate_pirq_msi((type == PCI_CAP_ID_MSIX) ?
> -                             "msi-x" : "msi", &irq, &pirq);
> +                             "msi-x" : "msi", &irq, &pirq, (XEN_ALLOC_IRQ | 
> XEN_ALLOC_PIRQ));
>               if (irq < 0 || pirq < 0)
>                       goto error;
>               printk(KERN_DEBUG "xen: msi --> irq=%d, pirq=%d\n", irq, pirq);
> diff --git a/drivers/xen/events.c b/drivers/xen/events.c
> index 6e5dd92..5de6a6c 100644
> --- a/drivers/xen/events.c
> +++ b/drivers/xen/events.c
> @@ -668,17 +668,21 @@ out:
>  #include <linux/msi.h>
>  #include "../pci/msi.h"
>  
> -void xen_allocate_pirq_msi(char *name, int *irq, int *pirq)
> +void xen_allocate_pirq_msi(char *name, int *irq, int *pirq, int alloc)
>  {
>       spin_lock(&irq_mapping_update_lock);
>  
> -     *irq = find_unbound_irq();
> -     if (*irq == -1)
> -             goto out;
> +     if (alloc & XEN_ALLOC_IRQ) {
> +             *irq = find_unbound_irq();
> +             if (*irq == -1)
> +                     goto out;
> +     }
>  
> -     *pirq = find_unbound_pirq(MAP_PIRQ_TYPE_MSI);
> -     if (*pirq == -1)
> -             goto out;
> +     if (alloc & XEN_ALLOC_PIRQ) {
> +             *pirq = find_unbound_pirq(MAP_PIRQ_TYPE_MSI);
> +             if (*pirq == -1)
> +                     goto out;
> +     }
>  
>       set_irq_chip_and_handler_name(*irq, &xen_pirq_chip,
>                                     handle_level_irq, name);
> @@ -766,6 +770,7 @@ int xen_destroy_irq(int irq)
>                       printk(KERN_WARNING "unmap irq failed %d\n", rc);
>                       goto out;
>               }
> +             pirq_to_irq[info->u.pirq.pirq] = -1;
>       }
>       irq_info[irq] = mk_unbound_info();
>  
> @@ -786,6 +791,11 @@ int xen_gsi_from_irq(unsigned irq)
>       return gsi_from_irq(irq);
>  }
>  
> +int xen_irq_from_pirq(unsigned pirq)
> +{
> +     return pirq_to_irq[pirq];
> +}
> +
>  int bind_evtchn_to_irq(unsigned int evtchn)
>  {
>       int irq;
> diff --git a/include/xen/events.h b/include/xen/events.h
> index 646dd17..00f53dd 100644
> --- a/include/xen/events.h
> +++ b/include/xen/events.h
> @@ -76,7 +76,9 @@ int xen_map_pirq_gsi(unsigned pirq, unsigned gsi, int 
> shareable, char *name);
>  
>  #ifdef CONFIG_PCI_MSI
>  /* Allocate an irq and a pirq to be used with MSIs. */
> -void xen_allocate_pirq_msi(char *name, int *irq, int *pirq);
> +#define XEN_ALLOC_PIRQ (1 << 0)
> +#define XEN_ALLOC_IRQ  (1 << 1)
> +void xen_allocate_pirq_msi(char *name, int *irq, int *pirq, int alloc_mask);
>  int xen_create_msi_irq(struct pci_dev *dev, struct msi_desc *msidesc, int 
> type);
>  #endif
>  
> @@ -89,4 +91,7 @@ int xen_vector_from_irq(unsigned pirq);
>  /* Return gsi allocated to pirq */
>  int xen_gsi_from_irq(unsigned pirq);
>  
> +/* Return irq from pirq */
> +int xen_irq_from_pirq(unsigned pirq);
> +
>  #endif       /* _XEN_EVENTS_H */
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@xxxxxxxxxxxxxxx
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel

<Prev in Thread] Current Thread [Next in Thread>