PCI: hv: Fix interrupt mapping for multi-MSI

According to Dexuan, the hypervisor folks beleive that multi-msi
allocations are not correct.  compose_msi_msg() will allocate multi-msi
one by one.  However, multi-msi is a block of related MSIs, with alignment
requirements.  In order for the hypervisor to allocate properly aligned
and consecutive entries in the IOMMU Interrupt Remapping Table, there
should be a single mapping request that requests all of the multi-msi
vectors in one shot.

Dexuan suggests detecting the multi-msi case and composing a single
request related to the first MSI.  Then for the other MSIs in the same
block, use the cached information.  This appears to be viable, so do it.

Suggested-by: Dexuan Cui <decui@microsoft.com>
Signed-off-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Reviewed-by: Dexuan Cui <decui@microsoft.com>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1652282599-21643-1-git-send-email-quic_jhugo@quicinc.com
Signed-off-by: Wei Liu <wei.liu@kernel.org>

diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c
index 5e2e637..e439b81 100644 (file)
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -1525,6 +1525,10 @@ static void hv_int_desc_free(struct hv_pci_dev *hpdev,
                u8 buffer[sizeof(struct pci_delete_interrupt)];
        } ctxt;
 
+       if (!int_desc->vector_count) {
+               kfree(int_desc);
+               return;
+       }
        memset(&ctxt, 0, sizeof(ctxt));
        int_pkt = (struct pci_delete_interrupt *)&ctxt.pkt.message;
        int_pkt->message_type.type =
@@ -1609,12 +1613,12 @@ static void hv_pci_compose_compl(void *context, struct pci_response *resp,
 
 static u32 hv_compose_msi_req_v1(
        struct pci_create_interrupt *int_pkt, struct cpumask *affinity,
-       u32 slot, u8 vector)
+       u32 slot, u8 vector, u8 vector_count)
 {
        int_pkt->message_type.type = PCI_CREATE_INTERRUPT_MESSAGE;
        int_pkt->wslot.slot = slot;
        int_pkt->int_desc.vector = vector;
-       int_pkt->int_desc.vector_count = 1;
+       int_pkt->int_desc.vector_count = vector_count;
        int_pkt->int_desc.delivery_mode = DELIVERY_MODE;
 
        /*
@@ -1637,14 +1641,14 @@ static int hv_compose_msi_req_get_cpu(struct cpumask *affinity)
 
 static u32 hv_compose_msi_req_v2(
        struct pci_create_interrupt2 *int_pkt, struct cpumask *affinity,
-       u32 slot, u8 vector)
+       u32 slot, u8 vector, u8 vector_count)
 {
        int cpu;
 
        int_pkt->message_type.type = PCI_CREATE_INTERRUPT_MESSAGE2;
        int_pkt->wslot.slot = slot;
        int_pkt->int_desc.vector = vector;
-       int_pkt->int_desc.vector_count = 1;
+       int_pkt->int_desc.vector_count = vector_count;
        int_pkt->int_desc.delivery_mode = DELIVERY_MODE;
        cpu = hv_compose_msi_req_get_cpu(affinity);
        int_pkt->int_desc.processor_array[0] =
@@ -1656,7 +1660,7 @@ static u32 hv_compose_msi_req_v2(
 
 static u32 hv_compose_msi_req_v3(
        struct pci_create_interrupt3 *int_pkt, struct cpumask *affinity,
-       u32 slot, u32 vector)
+       u32 slot, u32 vector, u8 vector_count)
 {
        int cpu;
 
@@ -1664,7 +1668,7 @@ static u32 hv_compose_msi_req_v3(
        int_pkt->wslot.slot = slot;
        int_pkt->int_desc.vector = vector;
        int_pkt->int_desc.reserved = 0;
-       int_pkt->int_desc.vector_count = 1;
+       int_pkt->int_desc.vector_count = vector_count;
        int_pkt->int_desc.delivery_mode = DELIVERY_MODE;
        cpu = hv_compose_msi_req_get_cpu(affinity);
        int_pkt->int_desc.processor_array[0] =
@@ -1695,6 +1699,8 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
        struct cpumask *dest;
        struct compose_comp_ctxt comp;
        struct tran_int_desc *int_desc;
+       struct msi_desc *msi_desc;
+       u8 vector, vector_count;
        struct {
                struct pci_packet pci_pkt;
                union {
@@ -1716,7 +1722,8 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
                return;
        }
 
-       pdev = msi_desc_to_pci_dev(irq_data_get_msi_desc(data));
+       msi_desc  = irq_data_get_msi_desc(data);
+       pdev = msi_desc_to_pci_dev(msi_desc);
        dest = irq_data_get_effective_affinity_mask(data);
        pbus = pdev->bus;
        hbus = container_of(pbus->sysdata, struct hv_pcibus_device, sysdata);
@@ -1729,6 +1736,36 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
        if (!int_desc)
                goto drop_reference;
 
+       if (!msi_desc->pci.msi_attrib.is_msix && msi_desc->nvec_used > 1) {
+               /*
+                * If this is not the first MSI of Multi MSI, we already have
+                * a mapping.  Can exit early.
+                */
+               if (msi_desc->irq != data->irq) {
+                       data->chip_data = int_desc;
+                       int_desc->address = msi_desc->msg.address_lo |
+                                           (u64)msi_desc->msg.address_hi << 32;
+                       int_desc->data = msi_desc->msg.data +
+                                        (data->irq - msi_desc->irq);
+                       msg->address_hi = msi_desc->msg.address_hi;
+                       msg->address_lo = msi_desc->msg.address_lo;
+                       msg->data = int_desc->data;
+                       put_pcichild(hpdev);
+                       return;
+               }
+               /*
+                * The vector we select here is a dummy value.  The correct
+                * value gets sent to the hypervisor in unmask().  This needs
+                * to be aligned with the count, and also not zero.  Multi-msi
+                * is powers of 2 up to 32, so 32 will always work here.
+                */
+               vector = 32;
+               vector_count = msi_desc->nvec_used;
+       } else {
+               vector = hv_msi_get_int_vector(data);
+               vector_count = 1;
+       }
+
        memset(&ctxt, 0, sizeof(ctxt));
        init_completion(&comp.comp_pkt.host_event);
        ctxt.pci_pkt.completion_func = hv_pci_compose_compl;
@@ -1739,7 +1776,8 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
                size = hv_compose_msi_req_v1(&ctxt.int_pkts.v1,
                                        dest,
                                        hpdev->desc.win_slot.slot,
-                                       hv_msi_get_int_vector(data));
+                                       vector,
+                                       vector_count);
                break;
 
        case PCI_PROTOCOL_VERSION_1_2:
@@ -1747,14 +1785,16 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
                size = hv_compose_msi_req_v2(&ctxt.int_pkts.v2,
                                        dest,
                                        hpdev->desc.win_slot.slot,
-                                       hv_msi_get_int_vector(data));
+                                       vector,
+                                       vector_count);
                break;
 
        case PCI_PROTOCOL_VERSION_1_4:
                size = hv_compose_msi_req_v3(&ctxt.int_pkts.v3,
                                        dest,
                                        hpdev->desc.win_slot.slot,
-                                       hv_msi_get_int_vector(data));
+                                       vector,
+                                       vector_count);
                break;
 
        default: