Re: [PATCH] pcie_root_port: Add disable_hotplug option

[Igor Mammedov <imammedo@redhat.com>]

On Tue, 18 Feb 2020 17:17:17 +0100
Julia Suvorova <jusual@redhat.com> wrote:

> Make hot-plug/hot-unplug on PCIe Root Ports optional to allow libvirt
> to manage it and restrict unplug for the entire machine. This is going
> to prevent user-initiated unplug in guests (Windows mostly).
> Usage:
>     -device pcie-root-port,disable-hotplug=true,...
> 
> Discussion related:
>     https://lists.gnu.org/archive/html/qemu-devel/2020-02/msg00530.html
> 
> Signed-off-by: Julia Suvorova <jusual@redhat.com>
> ---
>  hw/core/machine.c                  | 1 +
>  hw/pci-bridge/pcie_root_port.c     | 3 ++-
>  hw/pci-bridge/xio3130_downstream.c | 2 +-
>  hw/pci/pcie.c                      | 8 ++++++--
>  include/hw/pci/pcie.h              | 2 +-
>  include/hw/pci/pcie_port.h         | 1 +
>  6 files changed, 12 insertions(+), 5 deletions(-)
> 
> diff --git a/hw/core/machine.c b/hw/core/machine.c
> index 84812a1d1c..5ff698ac3c 100644
> --- a/hw/core/machine.c
> +++ b/hw/core/machine.c
> @@ -36,6 +36,7 @@ GlobalProperty hw_compat_4_2[] = {
>      { "usb-redir", "suppress-remote-wake", "off" },
>      { "qxl", "revision", "4" },
>      { "qxl-vga", "revision", "4" },
> +    { "pcie-root-port-base", "disable-hotplug", "false" },
this looks unnecessary as the property is 'off' by default

>  };
>  const size_t hw_compat_4_2_len = G_N_ELEMENTS(hw_compat_4_2);
>  
> diff --git a/hw/pci-bridge/pcie_root_port.c b/hw/pci-bridge/pcie_root_port.c
> index 0ba4e4dea4..d6a080bee8 100644
> --- a/hw/pci-bridge/pcie_root_port.c
> +++ b/hw/pci-bridge/pcie_root_port.c
> @@ -94,7 +94,7 @@ static void rp_realize(PCIDevice *d, Error **errp)
>  
>      pcie_cap_arifwd_init(d);
>      pcie_cap_deverr_init(d);
> -    pcie_cap_slot_init(d, s->slot);
> +    pcie_cap_slot_init(d, s);
>      pcie_cap_root_init(d);
>  
>      pcie_chassis_create(s->chassis);
> @@ -147,6 +147,7 @@ static Property rp_props[] = {
>      DEFINE_PROP_BIT(COMPAT_PROP_PCP, PCIDevice, cap_present,
>                      QEMU_PCIE_SLTCAP_PCP_BITNR, true),
>      DEFINE_PROP_BOOL("disable-acs", PCIESlot, disable_acs, false),
> +    DEFINE_PROP_BOOL("disable-hotplug", PCIESlot, disable_hotplug, false),
>      DEFINE_PROP_END_OF_LIST()
>  };
>  
> diff --git a/hw/pci-bridge/xio3130_downstream.c b/hw/pci-bridge/xio3130_downstream.c
> index 153a4acad2..04aae72cd6 100644
> --- a/hw/pci-bridge/xio3130_downstream.c
> +++ b/hw/pci-bridge/xio3130_downstream.c
> @@ -94,7 +94,7 @@ static void xio3130_downstream_realize(PCIDevice *d, Error **errp)
>      }
>      pcie_cap_flr_init(d);
>      pcie_cap_deverr_init(d);
> -    pcie_cap_slot_init(d, s->slot);
> +    pcie_cap_slot_init(d, s);
>      pcie_cap_arifwd_init(d);
>  
>      pcie_chassis_create(s->chassis);
> diff --git a/hw/pci/pcie.c b/hw/pci/pcie.c
> index 08718188bb..6dd9b89e21 100644
> --- a/hw/pci/pcie.c
> +++ b/hw/pci/pcie.c
> @@ -495,7 +495,7 @@ void pcie_cap_slot_unplug_request_cb(HotplugHandler *hotplug_dev,
>  
>  /* pci express slot for pci express root/downstream port
>     PCI express capability slot registers */
> -void pcie_cap_slot_init(PCIDevice *dev, uint16_t slot)
> +void pcie_cap_slot_init(PCIDevice *dev, PCIESlot *s)
>  {
>      uint32_t pos = dev->exp.exp_cap;
>  
> @@ -505,13 +505,17 @@ void pcie_cap_slot_init(PCIDevice *dev, uint16_t slot)
>      pci_long_test_and_clear_mask(dev->config + pos + PCI_EXP_SLTCAP,
>                                   ~PCI_EXP_SLTCAP_PSN);
>      pci_long_test_and_set_mask(dev->config + pos + PCI_EXP_SLTCAP,
> -                               (slot << PCI_EXP_SLTCAP_PSN_SHIFT) |
> +                               (s->slot << PCI_EXP_SLTCAP_PSN_SHIFT) |
>                                 PCI_EXP_SLTCAP_EIP |
>                                 PCI_EXP_SLTCAP_HPS |
>                                 PCI_EXP_SLTCAP_HPC |

why not to set it to begin with instead of clearing it later as afterthought?

Also only _HPC but _HPS is left, wouldn't it confuse guests?

>                                 PCI_EXP_SLTCAP_PIP |
>                                 PCI_EXP_SLTCAP_AIP |
>                                 PCI_EXP_SLTCAP_ABP);
> +    if (s->disable_hotplug) {
> +        pci_long_test_and_clear_mask(dev->config + pos + PCI_EXP_SLTCAP,
> +                                     PCI_EXP_SLTCAP_HPC);

> +    }
>  
>      if (dev->cap_present & QEMU_PCIE_SLTCAP_PCP) {
>          pci_long_test_and_set_mask(dev->config + pos + PCI_EXP_SLTCAP,
> diff --git a/include/hw/pci/pcie.h b/include/hw/pci/pcie.h
> index 7064875835..14c58ebdb6 100644
> --- a/include/hw/pci/pcie.h
> +++ b/include/hw/pci/pcie.h
> @@ -104,7 +104,7 @@ void pcie_cap_deverr_reset(PCIDevice *dev);
>  void pcie_cap_lnkctl_init(PCIDevice *dev);
>  void pcie_cap_lnkctl_reset(PCIDevice *dev);
>  
> -void pcie_cap_slot_init(PCIDevice *dev, uint16_t slot);
> +void pcie_cap_slot_init(PCIDevice *dev, PCIESlot *s);
>  void pcie_cap_slot_reset(PCIDevice *dev);
>  void pcie_cap_slot_get(PCIDevice *dev, uint16_t *slt_ctl, uint16_t *slt_sta);
>  void pcie_cap_slot_write_config(PCIDevice *dev,
> diff --git a/include/hw/pci/pcie_port.h b/include/hw/pci/pcie_port.h
> index 4b3d254b08..796fc8f3ab 100644
> --- a/include/hw/pci/pcie_port.h
> +++ b/include/hw/pci/pcie_port.h
> @@ -55,6 +55,7 @@ struct PCIESlot {
>  
>      /* Disable ACS (really for a pcie_root_port) */
>      bool        disable_acs;
> +    bool        disable_hotplug;
>      QLIST_ENTRY(PCIESlot) next;
>  };
>