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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v10 1/6] VT-d: Introduce new fields in msi_desc to track binding with guest interrupt
> From: Gao, Chao
> Sent: Wednesday, March 15, 2017 1:11 PM
>
> Currently, msi_msg_to_remap_entry is buggy when the live IRTE is in posted
> format. Straightforwardly, we can let caller specify which format of IRTE they
> want update to. But the problem is current callers are not aware of the
> binding with guest interrupt. Making all callers be aware of the binding with
> guest interrupt will cause a far more complicated change. Also some callings
> happen in interrupt context where they can't acquire d->event_lock to read
> struct hvm_pirq_dpci.
Above text is unclear to me. Are you trying to explain why current
code is buggy (which I don't get the point) or simply for mitigation
options which were once considered but dropped for some reasons?
>
> This patch introduces two new fields in msi_desc to track binding with a
> guest interrupt such that msi_msg_to_remap_entry() can get the binding and
> update IRTE accordingly. After that change, pi_update_irte() can utilize
> msi_msg_to_remap_entry() to update IRTE to posted format.
>
> Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx>
> Signed-off-by: Chao Gao <chao.gao@xxxxxxxxx>
> ---
> v10:
> - Newly added.
>
> xen/arch/x86/msi.c | 1 +
> xen/drivers/passthrough/vtd/intremap.c | 148
> +++++++--------------------------
> xen/include/asm-x86/msi.h | 2 +
> 3 files changed, 34 insertions(+), 117 deletions(-)
>
> diff --git a/xen/arch/x86/msi.c b/xen/arch/x86/msi.c index
> a868007..3374cd4 100644
> --- a/xen/arch/x86/msi.c
> +++ b/xen/arch/x86/msi.c
> @@ -578,6 +578,7 @@ static struct msi_desc *alloc_msi_entry(unsigned int
> nr)
> entry[nr].dev = NULL;
> entry[nr].irq = -1;
> entry[nr].remap_index = -1;
> + entry[nr].pi_desc = NULL;
> }
>
> return entry;
> diff --git a/xen/drivers/passthrough/vtd/intremap.c
> b/xen/drivers/passthrough/vtd/intremap.c
> index bfd468b..6202ece 100644
> --- a/xen/drivers/passthrough/vtd/intremap.c
> +++ b/xen/drivers/passthrough/vtd/intremap.c
> @@ -552,11 +552,12 @@ static int msi_msg_to_remap_entry(
> struct msi_desc *msi_desc, struct msi_msg *msg) {
> struct iremap_entry *iremap_entry = NULL, *iremap_entries;
> - struct iremap_entry new_ire;
> + struct iremap_entry new_ire = {{0}};
> struct msi_msg_remap_entry *remap_rte;
> unsigned int index, i, nr = 1;
> unsigned long flags;
> struct ir_ctrl *ir_ctrl = iommu_ir_ctrl(iommu);
> + const struct pi_desc *pi_desc = msi_desc->pi_desc;
>
> if ( msi_desc->msi_attrib.type == PCI_CAP_ID_MSI )
> nr = msi_desc->msi.nvec;
> @@ -595,33 +596,35 @@ static int msi_msg_to_remap_entry(
> GET_IREMAP_ENTRY(ir_ctrl->iremap_maddr, index,
> iremap_entries, iremap_entry);
>
> - memcpy(&new_ire, iremap_entry, sizeof(struct iremap_entry));
> -
> - /* Set interrupt remapping table entry */
> - new_ire.remap.fpd = 0;
> - new_ire.remap.dm = (msg->address_lo >> MSI_ADDR_DESTMODE_SHIFT)
> & 0x1;
> - new_ire.remap.tm = (msg->data >> MSI_DATA_TRIGGER_SHIFT) & 0x1;
> - new_ire.remap.dlm = (msg->data >> MSI_DATA_DELIVERY_MODE_SHIFT)
> & 0x1;
> - /* Hardware require RH = 1 for LPR delivery mode */
> - new_ire.remap.rh = (new_ire.remap.dlm == dest_LowestPrio);
> - new_ire.remap.avail = 0;
> - new_ire.remap.res_1 = 0;
> - new_ire.remap.vector = (msg->data >> MSI_DATA_VECTOR_SHIFT) &
> - MSI_DATA_VECTOR_MASK;
> - new_ire.remap.res_2 = 0;
> - if ( x2apic_enabled )
> - new_ire.remap.dst = msg->dest32;
> + if ( !pi_desc )
> + {
> + new_ire.remap.dm = msg->address_lo >>
> MSI_ADDR_DESTMODE_SHIFT;
> + new_ire.remap.tm = msg->data >> MSI_DATA_TRIGGER_SHIFT;
> + new_ire.remap.dlm = msg->data >>
> MSI_DATA_DELIVERY_MODE_SHIFT;
> + /* Hardware require RH = 1 for LPR delivery mode */
> + new_ire.remap.rh = (new_ire.remap.dlm == dest_LowestPrio);
> + new_ire.remap.vector = (msg->data >> MSI_DATA_VECTOR_SHIFT) &
> + MSI_DATA_VECTOR_MASK;
> + if ( x2apic_enabled )
> + new_ire.remap.dst = msg->dest32;
> + else
> + new_ire.remap.dst =
> + MASK_EXTR(msg->address_lo, MSI_ADDR_DEST_ID_MASK) << 8;
> + new_ire.remap.p = 1;
Old code also touches fpd, res_1/2/3/4, which are abandoned
above. Can you elaborate?
> + }
> else
> - new_ire.remap.dst = ((msg->address_lo >> MSI_ADDR_DEST_ID_SHIFT)
> - & 0xff) << 8;
> + {
> + new_ire.post.im = 1;
> + new_ire.post.vector = msi_desc->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.p = 1;
> + }
>
> if ( pdev )
> set_msi_source_id(pdev, &new_ire);
> else
> set_hpet_source_id(msi_desc->hpet_id, &new_ire);
> - new_ire.remap.res_3 = 0;
> - new_ire.remap.res_4 = 0;
> - new_ire.remap.p = 1; /* finally, set present bit */
>
> /* now construct new MSI/MSI-X rte entry */
> remap_rte = (struct msi_msg_remap_entry *)msg; @@ -902,42 +905,6
> @@ void iommu_disable_x2apic_IR(void)
> disable_qinval(drhd->iommu);
> }
>
> -static void setup_posted_irte(
> - struct iremap_entry *new_ire, const struct iremap_entry *old_ire,
> - const struct pi_desc *pi_desc, const uint8_t gvec)
> -{
> - memset(new_ire, 0, sizeof(*new_ire));
> -
> - /*
> - * 'im' filed decides whether the irte is in posted format (with value 1)
> - * or remapped format (with value 0), if the old irte is in remapped
> format,
> - * we copy things from remapped part in 'struct iremap_entry', otherwise,
> - * we copy from posted part.
> - */
> - if ( !old_ire->remap.im )
> - {
> - new_ire->post.p = old_ire->remap.p;
> - new_ire->post.fpd = old_ire->remap.fpd;
> - new_ire->post.sid = old_ire->remap.sid;
> - new_ire->post.sq = old_ire->remap.sq;
> - new_ire->post.svt = old_ire->remap.svt;
> - }
> - else
> - {
> - new_ire->post.p = old_ire->post.p;
> - new_ire->post.fpd = old_ire->post.fpd;
> - new_ire->post.sid = old_ire->post.sid;
> - new_ire->post.sq = old_ire->post.sq;
> - new_ire->post.svt = old_ire->post.svt;
> - new_ire->post.urg = old_ire->post.urg;
> - }
> -
> - new_ire->post.im = 1;
> - 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;
> -}
> -
> /*
> * This function is used to update the IRTE for posted-interrupt
> * when guest changes MSI/MSI-X information.
> @@ -946,17 +913,9 @@ int pi_update_irte(const struct vcpu *v, const struct
> pirq *pirq,
> const uint8_t gvec)
> {
> 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;
> + struct msi_desc *msi_desc;
> const struct pi_desc *pi_desc = &v->arch.hvm_vmx.pi_desc;
> - __uint128_t ret;
> + int rc;
>
> desc = pirq_spin_lock_irq_desc(pirq, NULL);
> if ( !desc )
> @@ -968,59 +927,14 @@ int pi_update_irte(const struct vcpu *v, const
> struct pirq *pirq,
> rc = -ENODEV;
> goto unlock_out;
> }
> -
> - pci_dev = msi_desc->dev;
> - if ( !pci_dev )
> - {
> - rc = -ENODEV;
> - goto unlock_out;
> - }
> -
> - remap_index = msi_desc->remap_index;
> + msi_desc->pi_desc = pi_desc;
> + msi_desc->gvec = gvec;
>
> spin_unlock_irq(&desc->lock);
>
> ASSERT(pcidevs_locked());
> -
> - /*
> - * FIXME: For performance reasons we should store the 'iommu' pointer
> in
> - * 'struct msi_desc' in some other place, so we don't need to waste
> - * time searching it here.
> - */
> - drhd = acpi_find_matched_drhd_unit(pci_dev);
> - if ( !drhd )
> - return -ENODEV;
> -
> - iommu = drhd->iommu;
> - ir_ctrl = iommu_ir_ctrl(iommu);
> - if ( !ir_ctrl )
> - return -ENODEV;
> -
> - spin_lock_irq(&ir_ctrl->iremap_lock);
> -
> - GET_IREMAP_ENTRY(ir_ctrl->iremap_maddr, remap_index,
> iremap_entries, p);
> -
> - old_ire = *p;
> -
> - /* Setup/Update interrupt remapping table entry. */
> - setup_posted_irte(&new_ire, &old_ire, pi_desc, gvec);
> - ret = cmpxchg16b(p, &old_ire, &new_ire);
> -
> - /*
> - * In the above, we use cmpxchg16 to atomically update the 128-bit IRTE,
> - * and the hardware cannot update the IRTE behind us, so the return
> value
> - * of cmpxchg16 should be the same as old_ire. This ASSERT validate it.
> - */
> - ASSERT(ret == old_ire.val);
> -
> - iommu_flush_cache_entry(p, sizeof(*p));
> - iommu_flush_iec_index(iommu, 0, remap_index);
> -
> - unmap_vtd_domain_page(iremap_entries);
> -
> - spin_unlock_irq(&ir_ctrl->iremap_lock);
> -
> - return 0;
> + rc = iommu_update_ire_from_msi(msi_desc, &msi_desc->msg);
> + return rc;
just "return iommu_update_ire..."
>
> unlock_out:
> spin_unlock_irq(&desc->lock);
> diff --git a/xen/include/asm-x86/msi.h b/xen/include/asm-x86/msi.h index
> 9c02945..3286692 100644
> --- a/xen/include/asm-x86/msi.h
> +++ b/xen/include/asm-x86/msi.h
> @@ -118,6 +118,8 @@ struct msi_desc {
> struct msi_msg msg; /* Last set MSI message */
>
> int remap_index; /* index in interrupt remapping table
> */
> + const void *pi_desc; /* PDA, indicates msi is delivered via
> VT-d PI */
what's PDA?
> + uint8_t gvec; /* guest vector. valid when pi_desc
> isn't NULL */
> };
>
> /*
> --
> 1.8.3.1
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