From b4b77778ecc5bfbd4e77de1b2fd5c1dd3c655f1f Mon Sep 17 00:00:00 2001 From: Jeffrey Hugo Date: Wed, 11 May 2022 09:23:02 -0600 Subject: [PATCH] PCI: hv: Reuse existing IRTE allocation in compose_msi_msg() Currently if compose_msi_msg() is called multiple times, it will free any previous IRTE allocation, and generate a new allocation. While nothing prevents this from occurring, it is extraneous when Linux could just reuse the existing allocation and avoid a bunch of overhead. However, when future IRTE allocations operate on blocks of MSIs instead of a single line, freeing the allocation will impact all of the lines. This could cause an issue where an allocation of N MSIs occurs, then some of the lines are retargeted, and finally the allocation is freed/reallocated. The freeing of the allocation removes all of the configuration for the entire block, which requires all the lines to be retargeted, which might not happen since some lines might already be unmasked/active. Signed-off-by: Jeffrey Hugo Reviewed-by: Dexuan Cui Tested-by: Dexuan Cui Tested-by: Michael Kelley Link: https://lore.kernel.org/r/1652282582-21595-1-git-send-email-quic_jhugo@quicinc.com Signed-off-by: Wei Liu --- drivers/pci/controller/pci-hyperv.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/drivers/pci/controller/pci-hyperv.c b/drivers/pci/controller/pci-hyperv.c index cf2fe5754fde..5e2e637ad344 100644 --- a/drivers/pci/controller/pci-hyperv.c +++ b/drivers/pci/controller/pci-hyperv.c @@ -1707,6 +1707,15 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg) u32 size; int ret; + /* Reuse the previous allocation */ + if (data->chip_data) { + int_desc = data->chip_data; + msg->address_hi = int_desc->address >> 32; + msg->address_lo = int_desc->address & 0xffffffff; + msg->data = int_desc->data; + return; + } + pdev = msi_desc_to_pci_dev(irq_data_get_msi_desc(data)); dest = irq_data_get_effective_affinity_mask(data); pbus = pdev->bus; @@ -1716,13 +1725,6 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg) if (!hpdev) goto return_null_message; - /* Free any previous message that might have already been composed. */ - if (data->chip_data) { - 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;