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115 lines
4.6 KiB
115 lines
4.6 KiB
9 months ago
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From 2f0febd6813c4ad7f52e43afb3ecce7aef3557e6 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 15:47:56 -0400
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Subject: [PATCH 08/11] s390x/pci: RPCIT second pass when mappings exhausted
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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: [1/4] 0b4500b9247725b1ef0b290bb85392300a618cac
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If we encounter a new mapping while the number of available DMA entries
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in vfio is 0, we are currently skipping that mapping which is a problem
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if we manage to free up DMA space after that within the same RPCIT --
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we will return to the guest with CC0 and have not mapped everything
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within the specified range. This issue was uncovered while testing
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changes to the s390 linux kernel iommu/dma code, where a different
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usage pattern was employed (new mappings start at the end of the
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aperture and work back towards the front, making us far more likely
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to encounter new mappings before invalidated mappings during a
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global refresh).
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Fix this by tracking whether any mappings were skipped due to vfio
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DMA limit hitting 0; when this occurs, we still continue the range
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and unmap/map anything we can - then we must re-run the range again
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to pickup anything that was missed. This must occur in a loop until
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all requests are satisfied (success) or we detect that we are still
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unable to complete all mappings (return ZPCI_RPCIT_ST_INSUFF_RES).
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Link: https://lore.kernel.org/linux-s390/20221019144435.369902-1-schnelle@linux.ibm.com/
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Fixes: 37fa32de70 ("s390x/pci: Honor DMA limits set by vfio")
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Reported-by: Niklas Schnelle <schnelle@linux.ibm.com>
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Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
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Message-Id: <20221028194758.204007-2-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 4a8d21ba50fc8625c3bd51dab903872952f95718)
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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 | 29 ++++++++++++++++++++++-------
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1 file changed, 22 insertions(+), 7 deletions(-)
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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 20a9bcc7af..7cc4bcf850 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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@@ -677,8 +677,9 @@ int rpcit_service_call(S390CPU *cpu, uint8_t r1, uint8_t r2, uintptr_t ra)
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S390PCIBusDevice *pbdev;
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S390PCIIOMMU *iommu;
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S390IOTLBEntry entry;
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- hwaddr start, end;
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+ hwaddr start, end, sstart;
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uint32_t dma_avail;
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+ bool again;
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if (env->psw.mask & PSW_MASK_PSTATE) {
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s390_program_interrupt(env, PGM_PRIVILEGED, ra);
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@@ -691,7 +692,7 @@ int rpcit_service_call(S390CPU *cpu, uint8_t r1, uint8_t r2, uintptr_t ra)
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}
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fh = env->regs[r1] >> 32;
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- start = env->regs[r2];
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+ sstart = start = env->regs[r2];
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end = start + env->regs[r2 + 1];
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pbdev = s390_pci_find_dev_by_fh(s390_get_phb(), fh);
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@@ -732,6 +733,9 @@ int rpcit_service_call(S390CPU *cpu, uint8_t r1, uint8_t r2, uintptr_t ra)
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goto err;
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}
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+ retry:
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+ start = sstart;
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+ again = false;
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while (start < end) {
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error = s390_guest_io_table_walk(iommu->g_iota, start, &entry);
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if (error) {
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@@ -739,13 +743,24 @@ int rpcit_service_call(S390CPU *cpu, uint8_t r1, uint8_t r2, uintptr_t ra)
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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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- (dma_avail > 0 || entry.perm == IOMMU_NONE)) {
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- dma_avail = s390_pci_update_iotlb(iommu, &entry);
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- entry.iova += TARGET_PAGE_SIZE;
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- entry.translated_addr += TARGET_PAGE_SIZE;
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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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+ dma_avail = s390_pci_update_iotlb(iommu, &entry);
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+ entry.iova += TARGET_PAGE_SIZE;
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+ entry.translated_addr += TARGET_PAGE_SIZE;
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+ } else {
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+ /*
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+ * We are unable to make a new mapping at this time, continue
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+ * on and hopefully free up more space. Then attempt another
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+ * pass.
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+ */
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+ again = true;
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+ break;
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+ }
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}
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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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if (error) {
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pbdev->state = ZPCI_FS_ERROR;
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--
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2.37.3
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