Re: [PATCH v5 11/17] vt-d: Add API to update IRTE when VT-d PI is used

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Wed, Aug 12, 2015 at 10:35:32AM +0800, Feng Wu wrote:
> This patch adds an API which is used to update the IRTE
> for posted-interrupt when guest changes MSI/MSI-X information.
> 
> CC: Yang Zhang <yang.z.zhang@intel.com>
> CC: Kevin Tian <kevin.tian@intel.com>
> CC: Keir Fraser <keir@xen.org>
> CC: Jan Beulich <jbeulich@suse.com>
> CC: Andrew Cooper <andrew.cooper3@citrix.com>
> Signed-off-by: Feng Wu <feng.wu@intel.com>
> Acked-by: Kevin Tian <kevin.tian@intel.com>
> ---
> v5:
> - Make some function parameters const
> - Call "spin_unlock_irq(&desc->lock);" a little eariler
> - Add "ASSERT(spin_is_locked(&pcidevs_lock))"
> - -EBADSLT -> -ENODEV, EBADSLT is removed in the lasted Xen
> 
> v4:
> - Don't inline setup_posted_irte()
> - const struct pi_desc *pi_desc for setup_posted_irte()
> - return -EINVAL when pirq_spin_lock_irq_desc() fails.
> - Make some variables const
> - Release irq desc lock earlier in pi_update_irte()
> - Remove the pointless do-while() loop when doing cmpxchg16b()
> 
> v3:
> - Remove "adding PDA_MASK()" when updating 'pda_l' and 'pda_h' for IRTE.
> - Change the return type of pi_update_irte() to int.
> - Remove some pointless printk message in pi_update_irte().
> - Use structure assignment instead of memcpy() for irte copy.
> 
>  xen/drivers/passthrough/vtd/intremap.c | 112 +++++++++++++++++++++++++++++++++
>  xen/drivers/passthrough/vtd/iommu.h    |   2 +
>  xen/include/asm-x86/iommu.h            |   2 +
>  3 files changed, 116 insertions(+)
> 
> diff --git a/xen/drivers/passthrough/vtd/intremap.c b/xen/drivers/passthrough/vtd/intremap.c
> index e9fffa6..8ec85d3 100644
> --- a/xen/drivers/passthrough/vtd/intremap.c
> +++ b/xen/drivers/passthrough/vtd/intremap.c
> @@ -899,3 +899,115 @@ void iommu_disable_x2apic_IR(void)
>      for_each_drhd_unit ( drhd )
>          disable_qinval(drhd->iommu);
>  }
> +
> +static void setup_posted_irte(

space before '{]'

> +    struct iremap_entry *new_ire,
> +    const struct pi_desc *pi_desc,
> +    const uint8_t gvec)

Not sure why but your parameters are on their own line? Shouldnt at least one
be with the function name - and then the rest on the same offset?

> +{
> +    new_ire->post.urg = 0;
> +    new_ire->post.vector = gvec;
> +    new_ire->post.pda_l = virt_to_maddr(pi_desc) >> (32 - PDA_LOW_BIT);
> +    new_ire->post.pda_h = virt_to_maddr(pi_desc) >> 32;
> +
> +    new_ire->post.res_1 = 0;
> +    new_ire->post.res_2 = 0;
> +    new_ire->post.res_3 = 0;
> +    new_ire->post.res_4 = 0;
> +    new_ire->post.res_5 = 0;
> +
> +    new_ire->post.im = 1;
> +}
> +
> +/*
> + * This function is used to update the IRTE for posted-interrupt
> + * when guest changes MSI/MSI-X information.
> + */
> +int pi_update_irte(
> +    const struct vcpu *v,
> +    const struct pirq *pirq,
> +    const uint8_t gvec)

Ditto - perhaps move these to be right after the function name?

> +{
> +    struct irq_desc *desc;
> +    const struct msi_desc *msi_desc;
> +    int remap_index;
> +    int rc = 0;
> +    const struct pci_dev *pci_dev;
> +    const struct acpi_drhd_unit *drhd;
> +    struct iommu *iommu;
> +    struct ir_ctrl *ir_ctrl;
> +    struct iremap_entry *iremap_entries = NULL, *p = NULL;
> +    struct iremap_entry new_ire, old_ire;
> +    const struct pi_desc *pi_desc = &v->arch.hvm_vmx.pi_desc;
> +    __uint128_t ret;
> +
> +    desc = pirq_spin_lock_irq_desc(pirq, NULL);
> +    if ( !desc )
> +        return -EINVAL;
> +
> +    msi_desc = desc->msi_desc;
> +    if ( !msi_desc )
> +    {
> +        rc = -ENODEV;
> +        goto unlock_out;
> +    }
> +
> +    pci_dev = msi_desc->dev;
> +    if ( !pci_dev )
> +    {
> +        rc = -ENODEV;
> +        goto unlock_out;
> +    }
> +
> +    remap_index = msi_desc->remap_index;
> +
> +    spin_unlock_irq(&desc->lock);
> +
> +    ASSERT(spin_is_locked(&pcidevs_lock));
> +
> +    /*
> +     * For performance concern, we will store the 'iommu' pointer in
> +     * 'struct msi_desc' in some other place, so we don't need to waste
> +     * time searching it here. I will fix this later.
> +     */
> +    drhd = acpi_find_matched_drhd_unit(pci_dev);
> +    if ( !drhd )
> +    {
> +        rc = -ENODEV;
> +        goto unlock_out;

But you already unlocked desc->lock (so doing unlock_out would do a second
spin unlock)? Should this be an return -ENODEV?

> +    }
> +
> +    iommu = drhd->iommu;
> +    ir_ctrl = iommu_ir_ctrl(iommu);
> +    if ( !ir_ctrl )
> +    {
> +        rc = -ENODEV;
> +        goto unlock_out;

Ditto.

> +    }
> +
> +    spin_lock_irq(&ir_ctrl->iremap_lock);
> +
> +    GET_IREMAP_ENTRY(ir_ctrl->iremap_maddr, remap_index, iremap_entries, p);
> +
> +    old_ire = new_ire = *p;
> +
> +    /* Setup/Update interrupt remapping table entry. */
> +    setup_posted_irte(&new_ire, pi_desc, gvec);
> +    ret = cmpxchg16b(p, &old_ire, &new_ire);
> +
> +    ASSERT(ret == *(__uint128_t *)&old_ire);
> +
> +    iommu_flush_cache_entry(p, sizeof(*p));

The other use sites of iommu_flush_cache_entry are sizeof(struct iremap_entry).
I think if you are doing this modification - then you should also have an
patch to modify the other code to be in sync.

Or just use the sizeof(struct ...).


> +    iommu_flush_iec_index(iommu, 0, remap_index);
> +
> +    unmap_vtd_domain_page(iremap_entries);
> +
> +    spin_unlock_irq(&ir_ctrl->iremap_lock);
> +
> +    return 0;
> +
> + unlock_out:
> +    spin_unlock_irq(&desc->lock);
> +
> +    return rc;
> +}
> diff --git a/xen/drivers/passthrough/vtd/iommu.h b/xen/drivers/passthrough/vtd/iommu.h
> index 6fca430..ff4ceb6 100644
> --- a/xen/drivers/passthrough/vtd/iommu.h
> +++ b/xen/drivers/passthrough/vtd/iommu.h
> @@ -322,6 +322,8 @@ struct iremap_entry {
>    };
>  };
> 

Perhaps a comment about it?
 
> +#define PDA_LOW_BIT    26
> +
>  /* Max intr remapping table page order is 8, as max number of IRTEs is 64K */
>  #define IREMAP_PAGE_ORDER  8
>  
> diff --git a/xen/include/asm-x86/iommu.h b/xen/include/asm-x86/iommu.h
> index 29203d7..92f0900 100644
> --- a/xen/include/asm-x86/iommu.h
> +++ b/xen/include/asm-x86/iommu.h
> @@ -31,6 +31,8 @@ int iommu_supports_eim(void);
>  int iommu_enable_x2apic_IR(void);
>  void iommu_disable_x2apic_IR(void);
>  
> +int pi_update_irte(const struct vcpu *v, const struct pirq *pirq, const uint8_t gvec);
> +
>  #endif /* !__ARCH_X86_IOMMU_H__ */
>  /*
>   * Local variables:
> -- 
> 2.1.0
> 
> 
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