126 lines
4.3 KiB
Diff
126 lines
4.3 KiB
Diff
From b972c5a2763a91024725c147cf1691ed8e180c7c Mon Sep 17 00:00:00 2001
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From: Matthew Rosato <mjrosato@linux.ibm.com>
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Date: Fri, 28 Oct 2022 15:47:57 -0400
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Subject: [PATCH 09/11] s390x/pci: coalesce unmap operations
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Cédric Le Goater <clg@redhat.com>
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RH-MergeRequest: 250: s390x/pci: reset ISM passthrough devices on shutdown and system reset
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RH-Bugzilla: 2163713
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RH-Acked-by: Thomas Huth <thuth@redhat.com>
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RH-Acked-by: Cornelia Huck <cohuck@redhat.com>
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RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
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RH-Commit: [2/4] 7b5ee38eca565f5a7cbede4b9883ba3a508fb46c
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Currently, each unmapped page is handled as an individual iommu
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region notification. Attempt to group contiguous unmap operations
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into fewer notifications to reduce overhead.
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Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
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Message-Id: <20221028194758.204007-3-mjrosato@linux.ibm.com>
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Reviewed-by: Eric Farman <farman@linux.ibm.com>
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Signed-off-by: Thomas Huth <thuth@redhat.com>
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(cherry picked from commit ef536007c3301bbd6a787e4c2210ea289adaa6f0)
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Signed-off-by: Cédric Le Goater <clg@redhat.com>
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---
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hw/s390x/s390-pci-inst.c | 51 ++++++++++++++++++++++++++++++++++++++++
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1 file changed, 51 insertions(+)
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diff --git a/hw/s390x/s390-pci-inst.c b/hw/s390x/s390-pci-inst.c
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index 7cc4bcf850..66e764f901 100644
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--- a/hw/s390x/s390-pci-inst.c
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+++ b/hw/s390x/s390-pci-inst.c
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@@ -640,6 +640,8 @@ static uint32_t s390_pci_update_iotlb(S390PCIIOMMU *iommu,
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}
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g_hash_table_remove(iommu->iotlb, &entry->iova);
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inc_dma_avail(iommu);
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+ /* Don't notify the iommu yet, maybe we can bundle contiguous unmaps */
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+ goto out;
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} else {
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if (cache) {
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if (cache->perm == entry->perm &&
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@@ -663,15 +665,44 @@ static uint32_t s390_pci_update_iotlb(S390PCIIOMMU *iommu,
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dec_dma_avail(iommu);
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}
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+ /*
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+ * All associated iotlb entries have already been cleared, trigger the
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+ * unmaps.
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+ */
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memory_region_notify_iommu(&iommu->iommu_mr, 0, event);
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out:
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return iommu->dma_limit ? iommu->dma_limit->avail : 1;
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}
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+static void s390_pci_batch_unmap(S390PCIIOMMU *iommu, uint64_t iova,
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+ uint64_t len)
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+{
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+ uint64_t remain = len, start = iova, end = start + len - 1, mask, size;
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+ IOMMUTLBEvent event = {
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+ .type = IOMMU_NOTIFIER_UNMAP,
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+ .entry = {
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+ .target_as = &address_space_memory,
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+ .translated_addr = 0,
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+ .perm = IOMMU_NONE,
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+ },
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+ };
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+
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+ while (remain >= TARGET_PAGE_SIZE) {
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+ mask = dma_aligned_pow2_mask(start, end, 64);
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+ size = mask + 1;
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+ event.entry.iova = start;
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+ event.entry.addr_mask = mask;
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+ memory_region_notify_iommu(&iommu->iommu_mr, 0, event);
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+ start += size;
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+ remain -= size;
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+ }
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+}
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+
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int rpcit_service_call(S390CPU *cpu, uint8_t r1, uint8_t r2, uintptr_t ra)
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{
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CPUS390XState *env = &cpu->env;
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+ uint64_t iova, coalesce = 0;
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uint32_t fh;
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uint16_t error = 0;
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S390PCIBusDevice *pbdev;
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@@ -742,6 +773,21 @@ int rpcit_service_call(S390CPU *cpu, uint8_t r1, uint8_t r2, uintptr_t ra)
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break;
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}
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+ /*
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+ * If this is an unmap of a PTE, let's try to coalesce multiple unmaps
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+ * into as few notifier events as possible.
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+ */
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+ if (entry.perm == IOMMU_NONE && entry.len == TARGET_PAGE_SIZE) {
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+ if (coalesce == 0) {
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+ iova = entry.iova;
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+ }
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+ coalesce += entry.len;
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+ } else if (coalesce > 0) {
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+ /* Unleash the coalesced unmap before processing a new map */
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+ s390_pci_batch_unmap(iommu, iova, coalesce);
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+ coalesce = 0;
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+ }
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+
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start += entry.len;
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while (entry.iova < start && entry.iova < end) {
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if (dma_avail > 0 || entry.perm == IOMMU_NONE) {
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@@ -759,6 +805,11 @@ int rpcit_service_call(S390CPU *cpu, uint8_t r1, uint8_t r2, uintptr_t ra)
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}
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}
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}
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+ if (coalesce) {
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+ /* Unleash the coalesced unmap before finishing rpcit */
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+ s390_pci_batch_unmap(iommu, iova, coalesce);
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+ coalesce = 0;
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+ }
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if (again && dma_avail > 0)
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goto retry;
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err:
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--
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2.37.3
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