On Tue, Jul 23, 2019 at 09:31:30AM +0000, Zhangbo (Oscar) wrote:
> If the PCI_EXP_LNKSTA_DLLLA capability is set by default, linux kernel will
> send
> PDC event to detect whether there is a device in pcie slot. If a device is
> pluged
> in the pcie-root-port at the same time, hot-plug device will send ABP + PDC
> events to the kernel. The VM kernel will wrongly unplug the device if two PDC
> events get too close. Thus we'd better set the PCI_EXP_LNKSTA_DLLLA
> capability only in hotplug callback.
>
> By the way, we should clean up the PCI_EXP_LNKSTA_DLLLA capability during
> unplug to avoid VM restart or migration failure which will enter the same
> abnormal scenario as above.
>
> Signed-off-by: Li Mingwang <limingw...@huawei.com>
> Signed-off-by: Fang Ying <fangyi...@huawei.com>
> Signed-off-by: Zhang Bo <oscar.zhan...@huawei.com>
I responded on v1 before seeing v2. As there's no change to patch
or commit log, same comments apply.
> ---
> hw/pci/pcie.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
> index a6beb56..174f392 100644
> --- a/hw/pci/pcie.c
> +++ b/hw/pci/pcie.c
> @@ -75,10 +75,6 @@ pcie_cap_v1_fill(PCIDevice *dev, uint8_t port, uint8_t
> type, uint8_t version)
> QEMU_PCI_EXP_LNKSTA_NLW(QEMU_PCI_EXP_LNK_X1) |
> QEMU_PCI_EXP_LNKSTA_CLS(QEMU_PCI_EXP_LNK_2_5GT));
>
> - if (dev->cap_present & QEMU_PCIE_LNKSTA_DLLLA) {
> - pci_word_test_and_set_mask(exp_cap + PCI_EXP_LNKSTA,
> - PCI_EXP_LNKSTA_DLLLA);
> - }
>
> /* We changed link status bits over time, and changing them across
> * migrations is generally fine as hardware changes them too.
> @@ -484,6 +480,11 @@ void pcie_cap_slot_unplug_request_cb(HotplugHandler
> *hotplug_dev,
> return;
> }
>
> + if (pci_dev->cap_present & QEMU_PCIE_LNKSTA_DLLLA) {
> + pci_word_test_and_clear_mask(exp_cap + PCI_EXP_LNKSTA,
> + PCI_EXP_LNKSTA_DLLLA);
> + }
> +
> pcie_cap_slot_push_attention_button(PCI_DEVICE(hotplug_dev));
> }
>
> --
> 1.8.3.1
