On Mon, Mar 25, 2024 at 03:07:24PM +0800, Jiqian Chen wrote:
> In current code, when guest does S3, virtio devices are reset due to
> the bit No_Soft_Reset is not set. After resetting, the display resources
> of virtio-gpu are destroyed, then the display can't come back and only
> show blank after resuming.
>
> Implement No_Soft_Reset bit of PCI_PM_CTRL register, then guest can check
> this bit, if this bit is set, the devices resetting will not be done, and
> then the display can work after resuming.
>
> Signed-off-by: Jiqian Chen <jiqian.c...@amd.com>
> ---
> hw/virtio/virtio-pci.c | 38 +++++++++++++++++++++++++++++++++-
> include/hw/virtio/virtio-pci.h | 5 +++++
> 2 files changed, 42 insertions(+), 1 deletion(-)
>
> diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> index 1a7039fb0c68..daafda315f8c 100644
> --- a/hw/virtio/virtio-pci.c
> +++ b/hw/virtio/virtio-pci.c
> @@ -2197,6 +2197,11 @@ static void virtio_pci_realize(PCIDevice *pci_dev,
> Error **errp)
> pcie_cap_lnkctl_init(pci_dev);
> }
>
> + if (proxy->flags & VIRTIO_PCI_FLAG_PM_NO_SOFT_RESET) {
> + pci_set_word(pci_dev->config + pos + PCI_PM_CTRL,
> + PCI_PM_CTRL_NO_SOFT_RESET);
> + }
> +
> if (proxy->flags & VIRTIO_PCI_FLAG_INIT_PM) {
> /* Init Power Management Control Register */
> pci_set_word(pci_dev->wmask + pos + PCI_PM_CTRL,
> @@ -2259,18 +2264,47 @@ static void virtio_pci_reset(DeviceState *qdev)
> }
> }
>
> +static bool device_no_need_reset(PCIDevice *dev)
I'd just call it virtio_pci_no_soft_reset() .
> +{
> + if (pci_is_express(dev)) {
A cleaner way to structure this is by reversing the test:
if (!pci_is_express(dev)) {
return false;
}
I would also check that pm_cap is actually set here.
> + uint16_t pmcsr;
> +
> + pmcsr = pci_get_word(dev->config + dev->exp.pm_cap + PCI_PM_CTRL);
> + /*
> + * When No_Soft_Reset bit is set and the device
> + * is in D3hot state, don't reset device
> + */
> + if ((pmcsr & PCI_PM_CTRL_NO_SOFT_RESET) &&
> + (pmcsr & PCI_PM_CTRL_STATE_MASK) == 3) {
> + return true;
And then here it will be
return (pmcsr & PCI_PM_CTRL_NO_SOFT_RESET) &&
(pmcsr & PCI_PM_CTRL_STATE_MASK) == 3;
> + }
> + }
> +
> + return false;
> +}
> +
> static void virtio_pci_bus_reset_hold(Object *obj)
> {
> PCIDevice *dev = PCI_DEVICE(obj);
> DeviceState *qdev = DEVICE(obj);
>
> + if (device_no_need_reset(dev)) {
> + return;
> + }
> +
> virtio_pci_reset(qdev);
>
> if (pci_is_express(dev)) {
> + uint16_t val = 0;
call it pm_ctrl
> + VirtIOPCIProxy *proxy = VIRTIO_PCI(dev);
> +
> pcie_cap_deverr_reset(dev);
> pcie_cap_lnkctl_reset(dev);
>
> - pci_set_word(dev->config + dev->exp.pm_cap + PCI_PM_CTRL, 0);
> + if (proxy->flags & VIRTIO_PCI_FLAG_PM_NO_SOFT_RESET) {
> + val |= PCI_PM_CTRL_NO_SOFT_RESET;
> + }
> + pci_set_word(dev->config + dev->exp.pm_cap + PCI_PM_CTRL, val);
There is no need to do it like this - only state is writeable
anyway. So simply
pci_word_test_and_clear_mask(dev->config + dev->exp.pm_cap +
PCI_PM_CTRL, PCI_PM_CTRL_STATE_MASK)
maybe we should actually check here:
if (proxy->flags & VIRTIO_PCI_FLAG_INIT_PM)
there's a chance commit 27ce0f3afc9 broke things for old machines
and we never noticed. If so that should be a separate bugfix patch though.
> }
> }
>
> @@ -2297,6 +2331,8 @@ static Property virtio_pci_properties[] = {
> VIRTIO_PCI_FLAG_INIT_LNKCTL_BIT, true),
> DEFINE_PROP_BIT("x-pcie-pm-init", VirtIOPCIProxy, flags,
> VIRTIO_PCI_FLAG_INIT_PM_BIT, true),
> + DEFINE_PROP_BIT("x-pcie-pm-no-soft-reset", VirtIOPCIProxy, flags,
> + VIRTIO_PCI_FLAG_PM_NO_SOFT_RESET_BIT, false),
> DEFINE_PROP_BIT("x-pcie-flr-init", VirtIOPCIProxy, flags,
> VIRTIO_PCI_FLAG_INIT_FLR_BIT, true),
> DEFINE_PROP_BIT("aer", VirtIOPCIProxy, flags,
> diff --git a/include/hw/virtio/virtio-pci.h b/include/hw/virtio/virtio-pci.h
> index 59d88018c16a..9e67ba38c748 100644
> --- a/include/hw/virtio/virtio-pci.h
> +++ b/include/hw/virtio/virtio-pci.h
> @@ -43,6 +43,7 @@ enum {
> VIRTIO_PCI_FLAG_INIT_FLR_BIT,
> VIRTIO_PCI_FLAG_AER_BIT,
> VIRTIO_PCI_FLAG_ATS_PAGE_ALIGNED_BIT,
> + VIRTIO_PCI_FLAG_PM_NO_SOFT_RESET_BIT,
> };
>
> /* Need to activate work-arounds for buggy guests at vmstate load. */
> @@ -79,6 +80,10 @@ enum {
> /* Init Power Management */
> #define VIRTIO_PCI_FLAG_INIT_PM (1 << VIRTIO_PCI_FLAG_INIT_PM_BIT)
>
> +/* Init The No_Soft_Reset bit of Power Management */
> +#define VIRTIO_PCI_FLAG_PM_NO_SOFT_RESET \
> + (1 << VIRTIO_PCI_FLAG_PM_NO_SOFT_RESET_BIT)
> +
> /* Init Function Level Reset capability */
> #define VIRTIO_PCI_FLAG_INIT_FLR (1 << VIRTIO_PCI_FLAG_INIT_FLR_BIT)
>
> --
> 2.34.1
