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s390x/pci: coalesce unmap operations

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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 <mjrosato@linux.ibm.com>
Message-Id: <20221028194758.204007-3-mjrosato@linux.ibm.com>
Reviewed-by: Eric Farman <farman@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
This commit is contained in:
Matthew Rosato 2022-10-28 15:47:57 -04:00 committed by Thomas Huth
parent 48804eebd4
commit ef536007c3
1 changed files with 51 additions and 0 deletions
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51
hw/s390x/s390-pci-inst.c
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@ -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: