From 11b5ce95beecfd51d1b17858d23fe9cbb0b5783f Mon Sep 17 00:00:00 2001 From: Corvin Köhne Date: Wed, 28 Aug 2024 15:43:25 +0200 Subject: vfio/igd: add new bar0 quirk to emulate BDSM mirror MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The BDSM register is mirrored into MMIO space at least for gen 11 and later devices. Unfortunately, the Windows driver reads the register value from MMIO space instead of PCI config space for those devices [1]. Therefore, we either have to keep a 1:1 mapping for the host and guest address or we have to emulate the MMIO register too. Using the igd in legacy mode is already hard due to it's many constraints. Keeping a 1:1 mapping may not work in all cases and makes it even harder to use. An MMIO emulation has to trap the whole MMIO page. This makes accesses to this page slower compared to using second level address translation. Nevertheless, it doesn't have any constraints and I haven't noticed any performance degradation yet making it a better solution. [1] https://github.com/projectacrn/acrn-hypervisor/blob/5c351bee0f6ae46250eefc07f44b4a31e770f3cf/devicemodel/hw/pci/passthrough.c#L650-L653 Signed-off-by: Corvin Köhne Reviewed-by: Alex Williamson --- hw/vfio/pci.h | 1 + 1 file changed, 1 insertion(+) (limited to 'hw/vfio/pci.h') diff --git a/hw/vfio/pci.h b/hw/vfio/pci.h index bf67df2fbc..5ad090a229 100644 --- a/hw/vfio/pci.h +++ b/hw/vfio/pci.h @@ -215,6 +215,7 @@ void vfio_setup_resetfn_quirk(VFIOPCIDevice *vdev); bool vfio_add_virt_caps(VFIOPCIDevice *vdev, Error **errp); void vfio_quirk_reset(VFIOPCIDevice *vdev); VFIOQuirk *vfio_quirk_alloc(int nr_mem); +void vfio_probe_igd_bar0_quirk(VFIOPCIDevice *vdev, int nr); void vfio_probe_igd_bar4_quirk(VFIOPCIDevice *vdev, int nr); extern const PropertyInfo qdev_prop_nv_gpudirect_clique; -- cgit 1.4.1