From 74fd0036deb585a139b63b26db025805ecedc37a Mon Sep 17 00:00:00 2001 From: Feng Wu Date: Wed, 27 Nov 2013 15:15:43 +0100 Subject: [PATCH] x86: properly handle MSI-X unmask operation from guests For a pass-through device with MSI-x capability, when guest tries to unmask the MSI-x interrupt for the passed through device, xen doesn't clear the mask bit for MSI-x in hardware in the following scenario, which will cause network disconnection: 1. Guest masks the MSI-x interrupt 2. Guest updates the address and data for it 3. Guest unmasks the MSI-x interrupt (This is the problematic step) In the step #3 above, Xen doesn't handle it well. When guest tries to unmask MSI-X interrupt, it traps to Xen, Xen just returns to Qemu if it notices that address or data has been modified by guest before, then Qemu will update Xen with the latest value of address/data by hypercall. However, in this whole process, the MSI-X interrupt unmask operation is missing, which means Xen doesn't clear the mask bit in hardware for the MSI-X interrupt, so it remains disabled, that is why it loses the network connection. This patch fixes this issue. Signed-off-by: Feng Wu Only latch the address if the guest really is unmasking the entry. Clean up the entire change. Signed-off-by: Jan Beulich Reviewed-by: Andrew Cooper --- xen/arch/x86/hvm/io.c | 3 +++ xen/arch/x86/hvm/vmsi.c | 16 ++++++++++++++++ xen/include/asm-x86/hvm/io.h | 1 + xen/include/asm-x86/hvm/vcpu.h | 2 ++ 4 files changed, 22 insertions(+) diff --git a/xen/arch/x86/hvm/io.c b/xen/arch/x86/hvm/io.c index 15e0b4c0ae..bf6309de26 100644 --- a/xen/arch/x86/hvm/io.c +++ b/xen/arch/x86/hvm/io.c @@ -300,7 +300,10 @@ void hvm_io_assist(ioreq_t *p) } if ( p->state == STATE_IOREQ_NONE ) + { + msix_write_completion(curr); vcpu_end_shutdown_deferral(curr); + } } static int dpci_ioport_read(uint32_t mport, ioreq_t *p) diff --git a/xen/arch/x86/hvm/vmsi.c b/xen/arch/x86/hvm/vmsi.c index 4826b4ad77..10e5f34954 100644 --- a/xen/arch/x86/hvm/vmsi.c +++ b/xen/arch/x86/hvm/vmsi.c @@ -293,7 +293,11 @@ static int msixtbl_write(struct vcpu *v, unsigned long address, /* exit to device model if address/data has been modified */ if ( test_and_clear_bit(nr_entry, &entry->table_flags) ) + { + if ( !(val & PCI_MSIX_VECTOR_BITMASK) ) + v->arch.hvm_vcpu.hvm_io.msix_unmask_address = address; goto out; + } virt = msixtbl_addr_to_virt(entry, address); if ( !virt ) @@ -528,3 +532,15 @@ void msixtbl_pt_cleanup(struct domain *d) spin_unlock(&d->arch.hvm_domain.msixtbl_list_lock); local_irq_restore(flags); } + +void msix_write_completion(struct vcpu *v) +{ + unsigned long ctrl_address = v->arch.hvm_vcpu.hvm_io.msix_unmask_address; + + if ( !ctrl_address ) + return; + + v->arch.hvm_vcpu.hvm_io.msix_unmask_address = 0; + if ( msixtbl_write(v, ctrl_address, 4, 0) != X86EMUL_OKAY ) + gdprintk(XENLOG_WARNING, "MSI-X write completion failure\n"); +} diff --git a/xen/include/asm-x86/hvm/io.h b/xen/include/asm-x86/hvm/io.h index 6f4cb96408..86db58de0a 100644 --- a/xen/include/asm-x86/hvm/io.h +++ b/xen/include/asm-x86/hvm/io.h @@ -124,6 +124,7 @@ void hvm_interrupt_post(struct vcpu *v, int vector, int type); void hvm_io_assist(ioreq_t *p); void hvm_dpci_eoi(struct domain *d, unsigned int guest_irq, union vioapic_redir_entry *ent); +void msix_write_completion(struct vcpu *); struct hvm_hw_stdvga { uint8_t sr_index; diff --git a/xen/include/asm-x86/hvm/vcpu.h b/xen/include/asm-x86/hvm/vcpu.h index a309389187..4f45060e7f 100644 --- a/xen/include/asm-x86/hvm/vcpu.h +++ b/xen/include/asm-x86/hvm/vcpu.h @@ -74,6 +74,8 @@ struct hvm_vcpu_io { * necessary retry through other than function return codes. */ bool_t mmio_retry, mmio_retrying; + + unsigned long msix_unmask_address; }; #define VMCX_EADDR (~0ULL) -- 2.30.2