ACK/Cmnt: [SRU][bionic:linux-azure-4.15][PATCH 1/1] UBUNTU: SAUCE: PCI: hv: Only reuse existing IRTE allocation for Multi-MSI
Marcelo Henrique Cerri
marcelo.cerri at canonical.com
Wed Nov 16 14:01:30 UTC 2022
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Hash: SHA512
On Tue, Nov 15 2022, John Cabaj wrote:
> BugLink: https://bugs.launchpad.net/bugs/1996093
>
> Fixes b4b77778ecc5 ("PCI: hv: Reuse existing IRTE allocation in compose_msi_msg()")
>
> Signed-off-by: John Cabaj <john.cabaj at canonical.com>
> ---
> drivers/pci/host/pci-hyperv.c | 68 +++++++++++++++++++++++++++--------
> 1 file changed, 53 insertions(+), 15 deletions(-)
>
> diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
> index 07100e7d87de..6465ac8d4193 100644
> --- a/drivers/pci/host/pci-hyperv.c
> +++ b/drivers/pci/host/pci-hyperv.c
> @@ -1101,7 +1101,7 @@ 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,
> + struct pci_create_interrupt *int_pkt,
> u32 slot, u8 vector, u8 vector_count)
> {
> int_pkt->message_type.type = PCI_CREATE_INTERRUPT_MESSAGE;
> @@ -1119,23 +1119,48 @@ static u32 hv_compose_msi_req_v1(
> return sizeof(*int_pkt);
> }
>
> -static u32 hv_compose_msi_req_v2(
> - struct pci_create_interrupt2 *int_pkt, struct cpumask *affinity,
> - u32 slot, u8 vector, u8 vector_count)
> +/*
> + * Create MSI w/ dummy vCPU set targeting just one vCPU, overwritten
> + * by subsequent retarget in hv_irq_unmask().
> + */
> +static int hv_compose_msi_req_get_cpu(struct cpumask *affinity)
> +{
> + return cpumask_first_and(affinity, cpu_online_mask);
> +}
> +
> +/*
> + * Make sure the dummy vCPU values for multi-MSI don't all point to vCPU0.
> + */
> +static int hv_compose_multi_msi_req_get_cpu(void)
> {
> + static DEFINE_SPINLOCK(multi_msi_cpu_lock);
> +
> + /* -1 means starting with CPU 0 */
> + static int cpu_next = -1;
> +
> + unsigned long flags;
> int cpu;
>
> + spin_lock_irqsave(&multi_msi_cpu_lock, flags);
> +
> + cpu_next = cpumask_next_wrap(cpu_next, cpu_online_mask, nr_cpu_ids,
> + false);
> + cpu = cpu_next;
> +
> + spin_unlock_irqrestore(&multi_msi_cpu_lock, flags);
> +
> + return cpu;
> +}
> +
> +static u32 hv_compose_msi_req_v2(
> + struct pci_create_interrupt2 *int_pkt, int cpu,
> + u32 slot, u8 vector, u8 vector_count)
> +{
> 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 = vector_count;
> int_pkt->int_desc.delivery_mode = dest_Fixed;
> -
> - /*
> - * Create MSI w/ dummy vCPU set targeting just one vCPU, overwritten
> - * by subsequent retarget in hv_irq_unmask().
> - */
> - cpu = cpumask_first_and(affinity, cpu_online_mask);
> int_pkt->int_desc.processor_array[0] =
> hv_cpu_number_to_vp_number(cpu);
> int_pkt->int_desc.processor_count = 1;
> @@ -1174,11 +1199,17 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
> } int_pkts;
> } __packed ctxt;
>
> + bool multi_msi;
> u32 size;
> int ret;
> + int cpu;
> +
> + msi_desc = irq_data_get_msi_desc(data);
> + multi_msi = !msi_desc->msi_attrib.is_msix &&
> + msi_desc->nvec_used > 1;
>
> /* Reuse the previous allocation */
> - if (data->chip_data) {
> + if (data->chip_data && multi_msi) {
> int_desc = data->chip_data;
> msg->address_hi = int_desc->address >> 32;
> msg->address_lo = int_desc->address & 0xffffffff;
> @@ -1186,7 +1217,6 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
> return;
> }
>
> - 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;
> @@ -1194,12 +1224,19 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
> hpdev = get_pcichild_wslot(hbus, devfn_to_wslot(pdev->devfn));
> if (!hpdev)
> goto return_null_message;
> +
> + /* Free any previous message that might have already been composed. */
> + if (data->chip_data && !multi_msi) {
> + int_desc = data->chip_data;
> + data->chip_data = NULL;
> + hv_int_desc_free(hpdev, int_desc);
> + }
>
> int_desc = kzalloc(sizeof(*int_desc), GFP_ATOMIC);
> if (!int_desc)
> goto drop_reference;
>
> - if (!msi_desc->msi_attrib.is_msix && msi_desc->nvec_used > 1) {
> + if (multi_msi) {
> /*
> * If this is not the first MSI of Multi MSI, we already have
> * a mapping. Can exit early.
> @@ -1224,9 +1261,11 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
> */
> vector = 32;
> vector_count = msi_desc->nvec_used;
> + cpu = hv_compose_multi_msi_req_get_cpu();
> } else {
> vector = hv_msi_get_int_vector(data);
> vector_count = 1;
> + cpu = hv_compose_msi_req_get_cpu(dest);
> }
>
> memset(&ctxt, 0, sizeof(ctxt));
> @@ -1237,7 +1276,6 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
> switch (pci_protocol_version) {
> case PCI_PROTOCOL_VERSION_1_1:
> size = hv_compose_msi_req_v1(&ctxt.int_pkts.v1,
> - dest,
> hpdev->desc.win_slot.slot,
> vector,
> vector_count);
> @@ -1246,7 +1284,7 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
> case PCI_PROTOCOL_VERSION_1_2:
> case PCI_PROTOCOL_VERSION_1_3:
> size = hv_compose_msi_req_v2(&ctxt.int_pkts.v2,
> - dest,
> + cpu,
> hpdev->desc.win_slot.slot,
> vector,
> vector_count);
> --
> 2.34.1
The patch looks good to me and it has good test results.
However the patch is very similar to the upstream one with some changes
to accommodate hv_compose_msi_req_get_cpu() that is missing in the 4.15
kernel. In this case, I think it makes more sense to keep the original
author and commit message and document the changes we had to include.
Since Tim is applying this patch I believe he can fix that when applying
it.
Acked-by: Marcelo Henrique Cerri <marcelo.cerri at canonical.com>
- --
Regards,
Marcelo
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