[PATCH v2] PCI: vmd: Only assign OSC features in bare metal OS.

[PATCH v2] PCI: vmd: Only assign OSC features in bare metal OS.

[Nirmal Patel]

Copy valid OSC flags from root bridge only when OS can provide correct
values. In virtual machine, all of the control features are disabled as
hypervisor will not passthrough root bridge information to VM.

Signed-off-by: Nirmal Patel <nirmal.patel@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
---
v2 : Added descriptive boolean and removed period from commit message.
---
 drivers/pci/controller/vmd.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/pci/controller/vmd.c b/drivers/pci/controller/vmd.c
index d4ae250d4bc6..760dfb4d9480 100644
--- a/drivers/pci/controller/vmd.c
+++ b/drivers/pci/controller/vmd.c
@@ -782,6 +782,7 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 	resource_size_t membar2_offset = 0x2000;
 	struct pci_bus *child;
 	struct pci_dev *dev;
+	bool vmd_in_guest;
 	int ret;

 	/*
@@ -862,14 +863,15 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 		.parent = res,
 	};

+	/* Non-zero offset means guest/direct assign view. */
+	vmd_in_guest = offset[0] || offset[1];
 	/*
 	 * Currently MSI remapping must be enabled in guest passthrough mode
 	 * due to some missing interrupt remapping plumbing. This is probably
 	 * acceptable because the guest is usually CPU-limited and MSI
 	 * remapping doesn't become a performance bottleneck.
 	 */
-	if (!(features & VMD_FEAT_CAN_BYPASS_MSI_REMAP) ||
-	    offset[0] || offset[1]) {
+	if (!(features & VMD_FEAT_CAN_BYPASS_MSI_REMAP) || vmd_in_guest) {
 		ret = vmd_alloc_irqs(vmd);
 		if (ret)
 			return ret;
@@ -910,8 +912,10 @@ static int vmd_enable_domain(struct vmd_dev *vmd, unsigned long features)
 		return -ENODEV;
 	}

-	vmd_copy_host_bridge_flags(pci_find_host_bridge(vmd->dev->bus),
-				   to_pci_host_bridge(vmd->bus->bridge));
+	/* Don't copy OSC control flags in VM, it disables features.*/
+	if (!vmd_in_guest)
+		vmd_copy_host_bridge_flags(pci_find_host_bridge(vmd->dev->bus),
+					 to_pci_host_bridge(vmd->bus->bridge));

 	vmd_attach_resources(vmd);
 	if (vmd->irq_domain)
--
2.43.0

Re: [PATCH v2] PCI: vmd: Only assign OSC features in bare metal OS.

[sashiko-bot]

> Copy valid OSC flags from root bridge only when OS can provide correct
> values. In virtual machine, all of the control features are disabled as
> hypervisor will not passthrough root bridge information to VM.
> 
> Signed-off-by: Nirmal Patel <nirmal.patel@linux.intel.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260710200558.499434-1-nirmal.patel@intel.com?part=1