Since Linux commit 7d5ec3d36123 ("PCI/MSI: Mask all unused MSI-X
entries"), kvmtool segfaults when the guest boots and tries to
disable all the MSI-X entries of a virtio device while MSI-X itself
is disabled.What Linux does is seems perfectly correct. However, kvmtool uses a different decoding depending on whether MSI-X is enabled for this device or not. Which seems pretty wrong. Cure the problem by removing the check against MSI-X being enabled, and simplify the whole logic which looked a bit odd. With this, Linux is back booting as a kvmtool guest with MSI-X. Cc: Andre Przywara <[email protected]> Cc: Alexandru Elisei <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Will Deacon <[email protected]> Signed-off-by: Marc Zyngier <[email protected]> --- include/kvm/virtio.h | 2 +- virtio/core.c | 12 ++++-------- virtio/pci.c | 7 ++----- 3 files changed, 7 insertions(+), 14 deletions(-) diff --git a/include/kvm/virtio.h b/include/kvm/virtio.h index 3a311f54..7047d36f 100644 --- a/include/kvm/virtio.h +++ b/include/kvm/virtio.h @@ -166,7 +166,7 @@ u16 virt_queue__get_head_iov(struct virt_queue *vq, struct iovec iov[], u16 virt_queue__get_inout_iov(struct kvm *kvm, struct virt_queue *queue, struct iovec in_iov[], struct iovec out_iov[], u16 *in, u16 *out); -int virtio__get_dev_specific_field(int offset, bool msix, u32 *config_off); +int virtio__get_dev_specific_field(int offset, u32 *config_off); enum virtio_trans { VIRTIO_PCI, diff --git a/virtio/core.c b/virtio/core.c index 90a661d1..afb09e90 100644 --- a/virtio/core.c +++ b/virtio/core.c @@ -169,16 +169,12 @@ void virtio_exit_vq(struct kvm *kvm, struct virtio_device *vdev, memset(vq, 0, sizeof(*vq)); } -int virtio__get_dev_specific_field(int offset, bool msix, u32 *config_off) +int virtio__get_dev_specific_field(int offset, u32 *config_off) { - if (msix) { - if (offset < 4) - return VIRTIO_PCI_O_MSIX; - else - offset -= 4; - } + if (offset < 24) + return VIRTIO_PCI_O_MSIX; - *config_off = offset; + *config_off = offset - 24; return VIRTIO_PCI_O_CONFIG; } diff --git a/virtio/pci.c b/virtio/pci.c index eb91f512..2a6e41f1 100644 --- a/virtio/pci.c +++ b/virtio/pci.c @@ -112,9 +112,7 @@ static bool virtio_pci__specific_data_in(struct kvm *kvm, struct virtio_device * { u32 config_offset; struct virtio_pci *vpci = vdev->virtio; - int type = virtio__get_dev_specific_field(offset - 20, - virtio_pci__msix_enabled(vpci), - &config_offset); + int type = virtio__get_dev_specific_field(offset, &config_offset); if (type == VIRTIO_PCI_O_MSIX) { switch (offset) { case VIRTIO_MSI_CONFIG_VECTOR: @@ -208,8 +206,7 @@ static bool virtio_pci__specific_data_out(struct kvm *kvm, struct virtio_device struct virtio_pci *vpci = vdev->virtio; u32 config_offset, vec; int gsi; - int type = virtio__get_dev_specific_field(offset - 20, virtio_pci__msix_enabled(vpci), - &config_offset); + int type = virtio__get_dev_specific_field(offset, &config_offset); if (type == VIRTIO_PCI_O_MSIX) { switch (offset) { case VIRTIO_MSI_CONFIG_VECTOR: -- 2.30.2 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
