Messages in this thread | | | Date | Wed, 19 Jan 2022 10:29:02 +0100 | Subject | Re: [PATCH v2 21/30] KVM: s390: pci: handle refresh of PCI translations | From | Pierre Morel <> |
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On 1/14/22 21:31, Matthew Rosato wrote: > Add a routine that will perform a shadow operation between a guest > and host IOAT. A subsequent patch will invoke this in response to > an 04 RPCIT instruction intercept. > > Signed-off-by: Matthew Rosato <mjrosato@linux.ibm.com> > --- > arch/s390/include/asm/kvm_pci.h | 1 + > arch/s390/include/asm/pci_dma.h | 1 + > arch/s390/kvm/pci.c | 208 +++++++++++++++++++++++++++++++- > arch/s390/kvm/pci.h | 8 +- > 4 files changed, 216 insertions(+), 2 deletions(-) > > diff --git a/arch/s390/include/asm/kvm_pci.h b/arch/s390/include/asm/kvm_pci.h > index 770849f13a70..fa90729a35cf 100644 > --- a/arch/s390/include/asm/kvm_pci.h > +++ b/arch/s390/include/asm/kvm_pci.h > @@ -30,6 +30,7 @@ struct kvm_zdev_ioat { > struct kvm_zdev { > struct zpci_dev *zdev; > struct kvm *kvm; > + u64 rpcit_count; > struct kvm_zdev_ioat ioat; > struct zpci_fib fib; > }; > diff --git a/arch/s390/include/asm/pci_dma.h b/arch/s390/include/asm/pci_dma.h > index 69e616d0712c..38004e0a4383 100644 > --- a/arch/s390/include/asm/pci_dma.h > +++ b/arch/s390/include/asm/pci_dma.h > @@ -52,6 +52,7 @@ enum zpci_ioat_dtype { > #define ZPCI_TABLE_ENTRIES (ZPCI_TABLE_SIZE / ZPCI_TABLE_ENTRY_SIZE) > #define ZPCI_TABLE_PAGES (ZPCI_TABLE_SIZE >> PAGE_SHIFT) > #define ZPCI_TABLE_ENTRIES_PAGES (ZPCI_TABLE_ENTRIES * ZPCI_TABLE_PAGES) > +#define ZPCI_TABLE_ENTRIES_PER_PAGE (ZPCI_TABLE_ENTRIES / ZPCI_TABLE_PAGES) > > #define ZPCI_TABLE_BITS 11 > #define ZPCI_PT_BITS 8 > diff --git a/arch/s390/kvm/pci.c b/arch/s390/kvm/pci.c > index 39c13c25a700..38d2b77ec565 100644 > --- a/arch/s390/kvm/pci.c > +++ b/arch/s390/kvm/pci.c > @@ -149,6 +149,208 @@ int kvm_s390_pci_aen_init(u8 nisc) > return rc; > } > > +static int dma_shadow_cpu_trans(struct kvm_vcpu *vcpu, unsigned long *entry, > + unsigned long *gentry) > +{ > + phys_addr_t gaddr = 0; > + unsigned long idx; > + struct page *page; > + kvm_pfn_t pfn; > + gpa_t addr; > + int rc = 0; > + > + if (pt_entry_isvalid(*gentry)) { > + /* pin and validate */ > + addr = *gentry & ZPCI_PTE_ADDR_MASK; > + idx = srcu_read_lock(&vcpu->kvm->srcu); > + page = gfn_to_page(vcpu->kvm, gpa_to_gfn(addr)); > + srcu_read_unlock(&vcpu->kvm->srcu, idx); > + if (is_error_page(page)) > + return -EIO; > + gaddr = page_to_phys(page) + (addr & ~PAGE_MASK); > + } > + > + if (pt_entry_isvalid(*entry)) { > + /* Either we are invalidating, replacing or no-op */ > + if (gaddr != 0) { > + if ((*entry & ZPCI_PTE_ADDR_MASK) == gaddr) { > + /* Duplicate */ > + kvm_release_pfn_dirty(*entry >> PAGE_SHIFT); > + } else { > + /* Replace */ > + pfn = (*entry >> PAGE_SHIFT); > + invalidate_pt_entry(entry); > + set_pt_pfaa(entry, gaddr); > + validate_pt_entry(entry); > + kvm_release_pfn_dirty(pfn); > + rc = 1; > + } > + } else { > + /* Invalidate */ > + pfn = (*entry >> PAGE_SHIFT); > + invalidate_pt_entry(entry); > + kvm_release_pfn_dirty(pfn); > + rc = 1; > + } > + } else if (gaddr != 0) { > + /* New Entry */ > + set_pt_pfaa(entry, gaddr); > + validate_pt_entry(entry); > + } > + > + return rc; > +} > + > +static unsigned long *dma_walk_guest_cpu_trans(struct kvm_vcpu *vcpu, > + struct kvm_zdev_ioat *ioat, > + dma_addr_t dma_addr) > +{ > + unsigned long *rto, *sto, *pto; > + unsigned int rtx, rts, sx, px, idx; > + struct page *page; > + gpa_t addr; > + int i; > + > + /* Pin guest segment table if needed */ > + rtx = calc_rtx(dma_addr); > + rto = ioat->head[(rtx / ZPCI_TABLE_ENTRIES_PER_PAGE)]; > + rts = rtx * ZPCI_TABLE_PAGES; > + if (!ioat->seg[rts]) { > + if (!reg_entry_isvalid(rto[rtx % ZPCI_TABLE_ENTRIES_PER_PAGE])) > + return NULL; > + sto = get_rt_sto(rto[rtx % ZPCI_TABLE_ENTRIES_PER_PAGE]); > + addr = ((u64)sto & ZPCI_RTE_ADDR_MASK); > + idx = srcu_read_lock(&vcpu->kvm->srcu); > + for (i = 0; i < ZPCI_TABLE_PAGES; i++) { > + page = gfn_to_page(vcpu->kvm, gpa_to_gfn(addr)); > + if (is_error_page(page)) { > + srcu_read_unlock(&vcpu->kvm->srcu, idx); > + return NULL; > + } > + ioat->seg[rts + i] = page_to_virt(page) + > + (addr & ~PAGE_MASK); > + addr += PAGE_SIZE; > + } > + srcu_read_unlock(&vcpu->kvm->srcu, idx); > + } > + > + /* Allocate pin pointers for another segment table if needed */ > + if (!ioat->pt[rtx]) { > + ioat->pt[rtx] = kcalloc(ZPCI_TABLE_ENTRIES, > + (sizeof(unsigned long *)), GFP_KERNEL); > + if (!ioat->pt[rtx]) > + return NULL; > + } > + /* Pin guest page table if needed */ > + sx = calc_sx(dma_addr); > + sto = ioat->seg[(rts + (sx / ZPCI_TABLE_ENTRIES_PER_PAGE))]; > + if (!ioat->pt[rtx][sx]) { > + if (!reg_entry_isvalid(sto[sx % ZPCI_TABLE_ENTRIES_PER_PAGE])) > + return NULL; > + pto = get_st_pto(sto[sx % ZPCI_TABLE_ENTRIES_PER_PAGE]); > + if (!pto) > + return NULL; > + addr = ((u64)pto & ZPCI_STE_ADDR_MASK); > + idx = srcu_read_lock(&vcpu->kvm->srcu); > + page = gfn_to_page(vcpu->kvm, gpa_to_gfn(addr)); > + srcu_read_unlock(&vcpu->kvm->srcu, idx); > + if (is_error_page(page)) > + return NULL; > + ioat->pt[rtx][sx] = page_to_virt(page) + (addr & ~PAGE_MASK); > + } > + pto = ioat->pt[rtx][sx]; > + > + /* Return guest PTE */ > + px = calc_px(dma_addr); > + return &pto[px]; > +} > + > + > +static int dma_table_shadow(struct kvm_vcpu *vcpu, struct zpci_dev *zdev, > + dma_addr_t dma_addr, size_t size) > +{ > + unsigned int nr_pages = PAGE_ALIGN(size) >> PAGE_SHIFT; > + struct kvm_zdev *kzdev = zdev->kzdev; > + unsigned long *entry, *gentry; > + int i, rc = 0, rc2; > + > + if (!nr_pages || !kzdev) > + return -EINVAL; > + > + mutex_lock(&kzdev->ioat.lock); > + if (!zdev->dma_table || !kzdev->ioat.head[0]) { > + rc = -EINVAL; > + goto out_unlock; > + } > + > + for (i = 0; i < nr_pages; i++) { > + gentry = dma_walk_guest_cpu_trans(vcpu, &kzdev->ioat, dma_addr); > + if (!gentry) > + continue; > + entry = dma_walk_cpu_trans(zdev->dma_table, dma_addr); > + > + if (!entry) { > + rc = -ENOMEM; > + goto out_unlock; > + } > + > + rc2 = dma_shadow_cpu_trans(vcpu, entry, gentry); > + if (rc2 < 0) { > + rc = -EIO; > + goto out_unlock; > + } > + dma_addr += PAGE_SIZE; > + rc += rc2; > + } > +
In case of error, shouldn't we invalidate the shadow tables entries we did validate until the error?
> +out_unlock: > + mutex_unlock(&kzdev->ioat.lock); > + return rc; > +} > + > +int kvm_s390_pci_refresh_trans(struct kvm_vcpu *vcpu, unsigned long req, > + unsigned long start, unsigned long size, > + u8 *status) > +{ > + struct zpci_dev *zdev; > + u32 fh = req >> 32; > + int rc; > + > + /* Make sure this is a valid device associated with this guest */ > + zdev = get_zdev_by_fh(fh); > + if (!zdev || !zdev->kzdev || zdev->kzdev->kvm != vcpu->kvm) { > + *status = 0;
Wouldn't it be interesting to add some debug information here. When would this appear?
Also if we have this error this looks like we have a VM problem, shouldn't we treat this in QEMU and return -EOPNOTSUPP ?
> + return -EINVAL; > + } > + > + /* Only proceed if the device is using the assist */ > + if (zdev->kzdev->ioat.head[0] == 0) > + return -EOPNOTSUPP; > + > + rc = dma_table_shadow(vcpu, zdev, start, size); > + if (rc < 0) { > + /* > + * If errors encountered during shadow operations, we must > + * fabricate status to present to the guest > + */ > + switch (rc) { > + case -ENOMEM: > + *status = KVM_S390_RPCIT_INS_RES; > + break; > + default: > + *status = KVM_S390_RPCIT_ERR; > + break; > + } > + } else if (rc > 0) { > + /* Host RPCIT must be issued */ > + rc = zpci_refresh_trans((u64) zdev->fh << 32, start, size, > + status); > + } > + zdev->kzdev->rpcit_count++; > + > + return rc; > +} > + > /* Modify PCI: Register floating adapter interruption forwarding */ > static int kvm_zpci_set_airq(struct zpci_dev *zdev) > { > @@ -620,6 +822,8 @@ EXPORT_SYMBOL_GPL(kvm_s390_pci_attach_kvm); > > int kvm_s390_pci_init(void) > { > + int rc; > + > aift = kzalloc(sizeof(struct zpci_aift), GFP_KERNEL); > if (!aift) > return -ENOMEM; > @@ -627,5 +831,7 @@ int kvm_s390_pci_init(void) > spin_lock_init(&aift->gait_lock); > mutex_init(&aift->lock); > > - return 0; > + rc = zpci_get_mdd(&aift->mdd); > + > + return rc; > } > diff --git a/arch/s390/kvm/pci.h b/arch/s390/kvm/pci.h > index 54355634df82..bb2be7fc3934 100644 > --- a/arch/s390/kvm/pci.h > +++ b/arch/s390/kvm/pci.h > @@ -18,6 +18,9 @@ > > #define KVM_S390_PCI_DTSM_MASK 0x40 > > +#define KVM_S390_RPCIT_INS_RES 0x10 > +#define KVM_S390_RPCIT_ERR 0x28 > + > struct zpci_gaite { > u32 gisa; > u8 gisc; > @@ -33,6 +36,7 @@ struct zpci_aift { > struct kvm_zdev **kzdev; > spinlock_t gait_lock; /* Protects the gait, used during AEN forward */ > struct mutex lock; /* Protects the other structures in aift */ > + u32 mdd; > }; > > extern struct zpci_aift *aift; > @@ -47,7 +51,9 @@ static inline struct kvm *kvm_s390_pci_si_to_kvm(struct zpci_aift *aift, > > int kvm_s390_pci_aen_init(u8 nisc); > void kvm_s390_pci_aen_exit(void); > - > +int kvm_s390_pci_refresh_trans(struct kvm_vcpu *vcpu, unsigned long req, > + unsigned long start, unsigned long end, > + u8 *status); > int kvm_s390_pci_init(void); > > #endif /* __KVM_S390_PCI_H */ >
-- Pierre Morel IBM Lab Boeblingen
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