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s390x/pci: add support for guests that request direct mapping

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When receiving a guest mpcifc(4) or mpcifc(6) instruction without the T
bit set, treat this as a request to perform direct mapping instead of
address translation.  In order to facilitate this, pin the entirety of
guest memory into the host iommu.

Pinning for the direct mapping case is handled via vfio and its memory
listener.  Additionally, ram discard settings are inherited from vfio:
coordinated discards (e.g. virtio-mem) are allowed while uncoordinated
discards (e.g. virtio-balloon) are disabled.

Subsequent guest DMA operations are all expected to be of the format
guest_phys+sdma, allowing them to be used as lookup into the host
iommu table.

Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Message-ID: <20250226210013.238349-2-mjrosato@linux.ibm.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>
This commit is contained in:
Matthew Rosato
2025-03-07 09:24:00 +01:00
committed by Thomas Huth
parent 9cbff6f29e
commit dfcee1ea4c
5 changed files with 76 additions and 9 deletions
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include/hw/s390x/s390-pci-bus.h
+3
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@@ -277,6 +277,7 @@ struct S390PCIIOMMU {
AddressSpace as;
MemoryRegion mr;
IOMMUMemoryRegion iommu_mr;
MemoryRegion *dm_mr;
bool enabled;
uint64_t g_iota;
uint64_t pba;
@@ -362,6 +363,7 @@ struct S390PCIBusDevice {
bool interp;
bool forwarding_assist;
bool aif;
bool rtr_avail;
QTAILQ_ENTRY(S390PCIBusDevice) link;
};
@@ -389,6 +391,7 @@ int pci_chsc_sei_nt2_have_event(void);
void s390_pci_sclp_configure(SCCB *sccb);
void s390_pci_sclp_deconfigure(SCCB *sccb);
void s390_pci_iommu_enable(S390PCIIOMMU *iommu);
void s390_pci_iommu_direct_map_enable(S390PCIIOMMU *iommu);
void s390_pci_iommu_disable(S390PCIIOMMU *iommu);
void s390_pci_generate_error_event(uint16_t pec, uint32_t fh, uint32_t fid,
uint64_t faddr, uint32_t e);