diff options
Diffstat (limited to 'hw/pci')
| -rw-r--r-- | hw/pci/pcie.c | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c index f8490a00de..c605d32dd4 100644 --- a/hw/pci/pcie.c +++ b/hw/pci/pcie.c @@ -610,6 +610,25 @@ void pcie_cap_slot_write_config(PCIDevice *dev, uint16_t slt_ctl, uint16_t slt_s uint16_t sltsta = pci_get_word(exp_cap + PCI_EXP_SLTSTA); if (ranges_overlap(addr, len, pos + PCI_EXP_SLTSTA, 2)) { + /* + * Guests tend to clears all bits during init. + * If they clear bits that weren't set this is racy and will lose events: + * not a big problem for manual button presses, but a problem for us. + * As a work-around, detect this and revert status to what it was + * before the write. + * + * Note: in theory this can be detected as a duplicate button press + * which cancels the previous press. Does not seem to happen in + * practice as guests seem to only have this bug during init. + */ +#define PCIE_SLOT_EVENTS (PCI_EXP_SLTSTA_ABP | PCI_EXP_SLTSTA_PFD | \ + PCI_EXP_SLTSTA_MRLSC | PCI_EXP_SLTSTA_PDC | \ + PCI_EXP_SLTSTA_CC) + + if (val & ~slt_sta & PCIE_SLOT_EVENTS) { + sltsta = (sltsta & ~PCIE_SLOT_EVENTS) | (slt_sta & PCIE_SLOT_EVENTS); + pci_set_word(exp_cap + PCI_EXP_SLTSTA, sltsta); + } hotplug_event_clear(dev); } |