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qemu_domain: add a PPC64 memLockLimit helper
There is a lot of documentation in the comments about how PPC64 handles passthrough VFIO devices to calculate the @memLockLimit. And more will be added with the PPC64 NVLink2 support code. Let's remove the PPC64 code from qemuDomainGetMemLockLimitBytes() body and put it into a helper function. This will simplify the flow of qemuDomainGetMemLockLimitBytes() that handles all the other platforms and improves readability of the PPC64 specifics. Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com> Reviewed-by: Erik Skultety <eskultet@redhat.com>
This commit is contained in:
Daniel Henrique Barboza
Erik Skultety
parent
cf7c521287
commit
7a686fd2ea
@ -10343,6 +10343,97 @@ qemuDomainUpdateCurrentMemorySize(virDomainObjPtr vm)
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}
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/**
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* getPPC64MemLockLimitBytes:
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* @def: domain definition
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*
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* A PPC64 helper that calculates the memory locking limit in order for
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* the guest to operate properly.
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*/
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static unsigned long long
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getPPC64MemLockLimitBytes(virDomainDefPtr def)
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{
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unsigned long long memKB = 0;
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unsigned long long baseLimit = 0;
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unsigned long long memory = 0;
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unsigned long long maxMemory = 0;
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unsigned long long passthroughLimit = 0;
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size_t i, nPCIHostBridges = 0;
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bool usesVFIO = false;
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for (i = 0; i < def->ncontrollers; i++) {
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virDomainControllerDefPtr cont = def->controllers[i];
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if (!virDomainControllerIsPSeriesPHB(cont))
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continue;
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nPCIHostBridges++;
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}
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for (i = 0; i < def->nhostdevs; i++) {
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virDomainHostdevDefPtr dev = def->hostdevs[i];
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if (dev->mode == VIR_DOMAIN_HOSTDEV_MODE_SUBSYS &&
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dev->source.subsys.type == VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_PCI &&
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dev->source.subsys.u.pci.backend == VIR_DOMAIN_HOSTDEV_PCI_BACKEND_VFIO) {
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usesVFIO = true;
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break;
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}
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}
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memory = virDomainDefGetMemoryTotal(def);
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if (def->mem.max_memory)
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maxMemory = def->mem.max_memory;
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else
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maxMemory = memory;
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/* baseLimit := maxMemory / 128 (a)
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* + 4 MiB * #PHBs + 8 MiB (b)
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*
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* (a) is the hash table
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*
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* (b) is accounting for the 32-bit DMA window - it could be either the
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* KVM accelerated TCE tables for emulated devices, or the VFIO
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* userspace view. The 4 MiB per-PHB (including the default one) covers
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* a 2GiB DMA window: default is 1GiB, but it's possible it'll be
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* increased to help performance. The 8 MiB extra should be plenty for
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* the TCE table index for any reasonable number of PHBs and several
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* spapr-vlan or spapr-vscsi devices (512kB + a tiny bit each) */
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baseLimit = maxMemory / 128 +
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4096 * nPCIHostBridges +
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8192;
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/* passthroughLimit := max( 2 GiB * #PHBs, (c)
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* memory (d)
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* + memory * 1/512 * #PHBs + 8 MiB ) (e)
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*
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* (c) is the pre-DDW VFIO DMA window accounting. We're allowing 2 GiB
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* rather than 1 GiB
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*
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* (d) is the with-DDW (and memory pre-registration and related
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* features) DMA window accounting - assuming that we only account RAM
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* once, even if mapped to multiple PHBs
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*
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* (e) is the with-DDW userspace view and overhead for the 64-bit DMA
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* window. This is based a bit on expected guest behaviour, but there
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* really isn't a way to completely avoid that. We assume the guest
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* requests a 64-bit DMA window (per PHB) just big enough to map all
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* its RAM. 4 kiB page size gives the 1/512; it will be less with 64
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* kiB pages, less still if the guest is mapped with hugepages (unlike
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* the default 32-bit DMA window, DDW windows can use large IOMMU
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* pages). 8 MiB is for second and further level overheads, like (b) */
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if (usesVFIO)
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passthroughLimit = MAX(2 * 1024 * 1024 * nPCIHostBridges,
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memory +
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memory / 512 * nPCIHostBridges + 8192);
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memKB = baseLimit + passthroughLimit;
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return memKB << 10;
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}
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/**
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* qemuDomainGetMemLockLimitBytes:
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* @def: domain definition
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@ -10374,84 +10465,8 @@ qemuDomainGetMemLockLimitBytes(virDomainDefPtr def)
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if (def->mem.locked)
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return VIR_DOMAIN_MEMORY_PARAM_UNLIMITED;
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if (ARCH_IS_PPC64(def->os.arch) && def->virtType == VIR_DOMAIN_VIRT_KVM) {
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unsigned long long maxMemory;
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unsigned long long memory;
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unsigned long long baseLimit;
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unsigned long long passthroughLimit = 0;
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size_t nPCIHostBridges = 0;
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bool usesVFIO = false;
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for (i = 0; i < def->ncontrollers; i++) {
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virDomainControllerDefPtr cont = def->controllers[i];
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if (!virDomainControllerIsPSeriesPHB(cont))
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continue;
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nPCIHostBridges++;
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}
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for (i = 0; i < def->nhostdevs; i++) {
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virDomainHostdevDefPtr dev = def->hostdevs[i];
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if (dev->mode == VIR_DOMAIN_HOSTDEV_MODE_SUBSYS &&
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dev->source.subsys.type == VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_PCI &&
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dev->source.subsys.u.pci.backend == VIR_DOMAIN_HOSTDEV_PCI_BACKEND_VFIO) {
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usesVFIO = true;
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break;
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}
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}
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memory = virDomainDefGetMemoryTotal(def);
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if (def->mem.max_memory)
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maxMemory = def->mem.max_memory;
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else
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maxMemory = memory;
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/* baseLimit := maxMemory / 128 (a)
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* + 4 MiB * #PHBs + 8 MiB (b)
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*
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* (a) is the hash table
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*
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* (b) is accounting for the 32-bit DMA window - it could be either the
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* KVM accelerated TCE tables for emulated devices, or the VFIO
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* userspace view. The 4 MiB per-PHB (including the default one) covers
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* a 2GiB DMA window: default is 1GiB, but it's possible it'll be
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* increased to help performance. The 8 MiB extra should be plenty for
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* the TCE table index for any reasonable number of PHBs and several
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* spapr-vlan or spapr-vscsi devices (512kB + a tiny bit each) */
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baseLimit = maxMemory / 128 +
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4096 * nPCIHostBridges +
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8192;
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/* passthroughLimit := max( 2 GiB * #PHBs, (c)
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* memory (d)
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* + memory * 1/512 * #PHBs + 8 MiB ) (e)
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*
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* (c) is the pre-DDW VFIO DMA window accounting. We're allowing 2 GiB
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* rather than 1 GiB
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*
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* (d) is the with-DDW (and memory pre-registration and related
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* features) DMA window accounting - assuming that we only account RAM
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* once, even if mapped to multiple PHBs
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*
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* (e) is the with-DDW userspace view and overhead for the 64-bit DMA
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* window. This is based a bit on expected guest behaviour, but there
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* really isn't a way to completely avoid that. We assume the guest
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* requests a 64-bit DMA window (per PHB) just big enough to map all
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* its RAM. 4 kiB page size gives the 1/512; it will be less with 64
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* kiB pages, less still if the guest is mapped with hugepages (unlike
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* the default 32-bit DMA window, DDW windows can use large IOMMU
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* pages). 8 MiB is for second and further level overheads, like (b) */
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if (usesVFIO)
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passthroughLimit = MAX(2 * 1024 * 1024 * nPCIHostBridges,
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memory +
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memory / 512 * nPCIHostBridges + 8192);
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memKB = baseLimit + passthroughLimit;
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goto done;
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}
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if (ARCH_IS_PPC64(def->os.arch) && def->virtType == VIR_DOMAIN_VIRT_KVM)
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return getPPC64MemLockLimitBytes(def);
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/* For device passthrough using VFIO the guest memory and MMIO memory
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* regions need to be locked persistent in order to allow DMA.
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