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PCI: hv: Fix interrupt mapping for multi-MSI
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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>
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@quic-jhugo @liuw
quic-jhugo authored and liuw committed May 11, 2022
1 parent b4b7777 commit a2bad84
Showing 1 changed file with 50 additions and 10 deletions.
60 changes: 50 additions & 10 deletions drivers/pci/controller/pci-hyperv.c
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Original file line number Diff line number Diff line change
Expand Up @@ -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 =
Expand Down Expand Up @@ -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;

/*
Expand All @@ -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] =
Expand All @@ -1656,15 +1660,15 @@ 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;

int_pkt->message_type.type = PCI_CREATE_INTERRUPT_MESSAGE3;
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] =
Expand Down Expand Up @@ -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 {
Expand All @@ -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);
Expand All @@ -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;
Expand All @@ -1739,22 +1776,25 @@ 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:
case PCI_PROTOCOL_VERSION_1_3:
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:
Expand Down

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