Re: [PATCH v2 21/30] KVM: s390: pci: handle refresh of PCI translations
From: Pierre Morel
Date: Wed Jan 19 2022 - 04:27:33 EST
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@xxxxxxxxxxxxx>
---
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