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