Honor the disabled setting for MSI-X interrupts for passthrough devices.

Add a new ioctl to disable all MSI-X interrupts for a PCI passthrough
device and invoke it if a write to the MSI-X capability registers
disables MSI-X.  This avoids leaving MSI-X interrupts enabled on the
host if a guest device driver has disabled them (e.g. as part of
detaching a guest device driver).

This was found by Chelsio QA when testing that a Linux guest could
switch from MSI-X to MSI interrupts when using the cxgb4vf driver.

While here, explicitly fail requests to enable MSI on a passthrough
device if MSI-X is enabled and vice versa.

Reported by:	Sony Arpita Das @ Chelsio
Reviewed by:	grehan, markj
MFC after:	2 weeks
Sponsored by:	Chelsio Communications
Differential Revision:	https://reviews.freebsd.org/D27212

lib/libvmmapi/vmmapi.c

@@ -1017,6 +1017,19 @@ vm_setup_pptdev_msix(struct vmctx *ctx, int vcpu, int bus, int slot, int func,
 	return ioctl(ctx->fd, VM_PPTDEV_MSIX, &pptmsix);
 }
 
+int
+vm_disable_pptdev_msix(struct vmctx *ctx, int bus, int slot, int func)
+{
+	struct vm_pptdev ppt;
+
+	bzero(&ppt, sizeof(ppt));
+	ppt.bus = bus;
+	ppt.slot = slot;
+	ppt.func = func;
+
+	return ioctl(ctx->fd, VM_PPTDEV_DISABLE_MSIX, &ppt);
+}
+
 uint64_t *
 vm_get_stats(struct vmctx *ctx, int vcpu, struct timeval *ret_tv,
 	     int *ret_entries)
@@ -1641,7 +1654,8 @@ vm_get_ioctls(size_t *len)
 	    VM_ISA_DEASSERT_IRQ, VM_ISA_PULSE_IRQ, VM_ISA_SET_IRQ_TRIGGER,
 	    VM_SET_CAPABILITY, VM_GET_CAPABILITY, VM_BIND_PPTDEV,
 	    VM_UNBIND_PPTDEV, VM_MAP_PPTDEV_MMIO, VM_PPTDEV_MSI,
-	    VM_PPTDEV_MSIX, VM_INJECT_NMI, VM_STATS, VM_STAT_DESC,
+	    VM_PPTDEV_MSIX, VM_PPTDEV_DISABLE_MSIX,
+	    VM_INJECT_NMI, VM_STATS, VM_STAT_DESC,
 	    VM_SET_X2APIC_STATE, VM_GET_X2APIC_STATE,
 	    VM_GET_HPET_CAPABILITIES, VM_GET_GPA_PMAP, VM_GLA2GPA,
 	    VM_GLA2GPA_NOFAULT,

lib/libvmmapi/vmmapi.h

@@ -181,6 +181,7 @@ int	vm_setup_pptdev_msi(struct vmctx *ctx, int vcpu, int bus, int slot,
 int	vm_setup_pptdev_msix(struct vmctx *ctx, int vcpu, int bus, int slot,
 	    int func, int idx, uint64_t addr, uint64_t msg,
 	    uint32_t vector_control);
+int	vm_disable_pptdev_msix(struct vmctx *ctx, int bus, int slot, int func);
 
 int	vm_get_intinfo(struct vmctx *ctx, int vcpu, uint64_t *i1, uint64_t *i2);
 int	vm_set_intinfo(struct vmctx *ctx, int vcpu, uint64_t exit_intinfo);

sys/amd64/include/vmm_dev.h

@@ -301,6 +301,7 @@ enum {
 	IOCNUM_MAP_PPTDEV_MMIO = 42,
 	IOCNUM_PPTDEV_MSI = 43,
 	IOCNUM_PPTDEV_MSIX = 44,
+	IOCNUM_PPTDEV_DISABLE_MSIX = 45,
 
 	/* statistics */
 	IOCNUM_VM_STATS = 50, 
@@ -413,6 +414,8 @@ enum {
 	_IOW('v', IOCNUM_PPTDEV_MSI, struct vm_pptdev_msi)
 #define	VM_PPTDEV_MSIX \
 	_IOW('v', IOCNUM_PPTDEV_MSIX, struct vm_pptdev_msix)
+#define	VM_PPTDEV_DISABLE_MSIX \
+	_IOW('v', IOCNUM_PPTDEV_DISABLE_MSIX, struct vm_pptdev)
 #define VM_INJECT_NMI \
 	_IOW('v', IOCNUM_INJECT_NMI, struct vm_nmi)
 #define	VM_STATS \

sys/amd64/vmm/io/ppt.c

@@ -518,6 +518,10 @@ ppt_setup_msi(struct vm *vm, int vcpu, int bus, int slot, int func,
 	if (ppt->vm != vm)		/* Make sure we own this device */
 		return (EBUSY);
 
+	/* Reject attempts to enable MSI while MSI-X is active. */
+	if (ppt->msix.num_msgs != 0 && numvec != 0)
+		return (EBUSY);
+
 	/* Free any allocated resources */
 	ppt_teardown_msi(ppt);
 
@@ -607,6 +611,10 @@ ppt_setup_msix(struct vm *vm, int vcpu, int bus, int slot, int func,
 	if (ppt->vm != vm)		/* Make sure we own this device */
 		return (EBUSY);
 
+	/* Reject attempts to enable MSI-X while MSI is active. */
+	if (ppt->msi.num_msgs != 0)
+		return (EBUSY);
+
 	dinfo = device_get_ivars(ppt->dev);
 	if (!dinfo) 
 		return (ENXIO);
@@ -700,3 +708,18 @@ ppt_setup_msix(struct vm *vm, int vcpu, int bus, int slot, int func,
 
 	return (0);
 }
+
+int
+ppt_disable_msix(struct vm *vm, int bus, int slot, int func)
+{
+	struct pptdev *ppt;
+
+	ppt = ppt_find(bus, slot, func);
+	if (ppt == NULL)
+		return (ENOENT);
+	if (ppt->vm != vm)		/* Make sure we own this device */
+		return (EBUSY);
+
+	ppt_teardown_msix(ppt);
+	return (0);
+}

sys/amd64/vmm/io/ppt.h

@@ -38,6 +38,7 @@ int	ppt_setup_msi(struct vm *vm, int vcpu, int bus, int slot, int func,
 		      uint64_t addr, uint64_t msg, int numvec);
 int	ppt_setup_msix(struct vm *vm, int vcpu, int bus, int slot, int func,
 		int idx, uint64_t addr, uint64_t msg, uint32_t vector_control);
+int	ppt_disable_msix(struct vm *vm, int bus, int slot, int func);
 int	ppt_assigned_devices(struct vm *vm);
 bool	ppt_is_mmio(struct vm *vm, vm_paddr_t gpa);
 

sys/amd64/vmm/vmm_dev.c

@@ -514,6 +514,11 @@ vmmdev_ioctl(struct cdev *cdev, u_long cmd, caddr_t data, int fflag,
 				       pptmsix->addr, pptmsix->msg,
 				       pptmsix->vector_control);
 		break;
+	case VM_PPTDEV_DISABLE_MSIX:
+		pptdev = (struct vm_pptdev *)data;
+		error = ppt_disable_msix(sc->vm, pptdev->bus, pptdev->slot,
+					 pptdev->func);
+		break;
 	case VM_MAP_PPTDEV_MMIO:
 		pptmmio = (struct vm_pptdev_mmio *)data;
 		error = ppt_map_mmio(sc->vm, pptmmio->bus, pptmmio->slot,

usr.sbin/bhyve/pci_passthru.c

@@ -869,6 +869,11 @@ passthru_cfgwrite(struct vmctx *ctx, int vcpu, struct pci_devinst *pi,
 				if (error)
 					err(1, "vm_setup_pptdev_msix");
 			}
+		} else {
+			error = vm_disable_pptdev_msix(ctx, sc->psc_sel.pc_bus,
+			    sc->psc_sel.pc_dev, sc->psc_sel.pc_func);
+			if (error)
+				err(1, "vm_disable_pptdev_msix");
 		}
 		return (0);
 	}