KVM: PPC: Book3S HV: XIVE: fix page offset when clearing ESB pages

Under XIVE, the ESB pages of an interrupt are used for interrupt management (EOI) and triggering. They are made available to guests through a mapping of the XIVE KVM device.

When a device is passed-through, the passthru_irq helpers, kvmppc_xive_set_mapped() and kvmppc_xive_clr_mapped(), clear the ESB pages of the guest IRQ number being mapped and let the VM fault handler repopulate with the correct page.

The ESB pages are mapped at offset 4 (KVM_XIVE_ESB_PAGE_OFFSET) in the KVM device mapping. Unfortunately, this offset was not taken into account when clearing the pages. This lead to issues with the

passthrough devices for which the interrupts were not functional under some guest configuration (tg3 and single CPU) or in any configuration

(e1000e adapter).

Signed-off-by Cédric Le Goater <[email protected]>

---

if unmap_mapping_pages() could be called from a module, we would simplify a bit this code.

 arch/powerpc/kvm/book3s_xive_native.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

arch/powerpc/kvm/book3s_xive_native.c +2 -1

index 8b762e3ebbc5..5596c8ec221a 100644
@@ -172,6 +172,7 @@ int kvmppc_xive_native_connect_vcpu(struct kvm_device *dev,
 static int kvmppc_xive_native_reset_mapped(struct kvm *kvm, unsigned long irq)
 {
 	struct kvmppc_xive *xive = kvm->arch.xive;
+	pgoff_t esb_pgoff = KVM_XIVE_ESB_PAGE_OFFSET + irq * 2;
 
 	if (irq >= KVMPPC_XIVE_NR_IRQS)
 		return -EINVAL;

@@ -185,7 +186,7 @@ static int kvmppc_xive_native_reset_mapped(struct kvm *kvm, unsigned long irq)
 	mutex_lock(&xive->mapping_lock);
 	if (xive->mapping)
 		unmap_mapping_range(xive->mapping,
-				    irq * (2ull << PAGE_SHIFT),
+				    esb_pgoff << PAGE_SHIFT,
 				    2ull << PAGE_SHIFT, 1);
 	mutex_unlock(&xive->mapping_lock);
 	return 0;

Under XIVE, the ESB pages of an interrupt are used for interrupt management (EOI) and triggering. They are made available to guests through a mapping of the XIVE KVM device.

When a device is passed-through, the passthru_irq helpers, kvmppc_xive_set_mapped() and kvmppc_xive_clr_mapped(), clear the ESB pages of the guest IRQ number being mapped and let the VM fault handler repopulate with the correct page.

The ESB pages are mapped at offset 4 (KVM_XIVE_ESB_PAGE_OFFSET) in the KVM device mapping. Unfortunately, this offset was not taken into account when clearing the pages. This lead to issues with the passthrough devices for which the interrupts were not functional under some guest configuration (tg3 and single CPU) or in any configuration (e1000e adapter).

Signed-off-by Cédric Le Goater <[email protected]>