Hi Leon,
On 2/8/21 4:21 PM, Leon Romanovsky wrote:
On Wed, Feb 03, 2021 at 12:56:44PM -0800, Megha Dey wrote:
From: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
The pci_subdevice_msi_create_irq_domain() should fail if the underlying
platform is not able to support IMS (Interrupt Message Storage). Otherwise,
the isolation of interrupt is not guaranteed.
For x86, IMS is only supported on bare metal for now. We could enable it
in the virtualization environments in the future if interrupt HYPERCALL
domain is supported or the hardware has the capability of interrupt
isolation for subdevices.
Cc: David Woodhouse <dwmw@xxxxxxxxxxxx>
Cc: Leon Romanovsky <leon@xxxxxxxxxx>
Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
Suggested-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/linux-pci/87pn4nk7nn.fsf@xxxxxxxxxxxxxxxxxxxxxxx/
Link: https://lore.kernel.org/linux-pci/877dqrnzr3.fsf@xxxxxxxxxxxxxxxxxxxxxxx/
Link: https://lore.kernel.org/linux-pci/877dqqmc2h.fsf@xxxxxxxxxxxxxxxxxxxxxxx/
Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
Signed-off-by: Megha Dey <megha.dey@xxxxxxxxx>
---
arch/x86/pci/common.c | 74 +++++++++++++++++++++++++++++++++++++++++++++
drivers/base/platform-msi.c | 8 +++++
include/linux/msi.h | 1 +
3 files changed, 83 insertions(+)
diff --git a/arch/x86/pci/common.c b/arch/x86/pci/common.c
index 3507f45..263ccf6 100644
--- a/arch/x86/pci/common.c
+++ b/arch/x86/pci/common.c
@@ -12,6 +12,8 @@
#include <linux/init.h>
#include <linux/dmi.h>
#include <linux/slab.h>
+#include <linux/iommu.h>
+#include <linux/msi.h>
#include <asm/acpi.h>
#include <asm/segment.h>
@@ -724,3 +726,75 @@ struct pci_dev *pci_real_dma_dev(struct pci_dev *dev)
return dev;
}
#endif
+
+#ifdef CONFIG_DEVICE_MSI
Sorry for my naive question, but I see it in all your patches in this series
and wonder why did you wrap everything with ifdefs?.
The added code is only called when DEVICE_MSI is configured.
All *.c code is wrapped with those ifdefs, which is hard to navigate and
unlikely to give any code/size optimization benefit if kernel is compiled
without CONFIG_DEVICE_MSI. The more common approach is to put those
ifdef in the public header files and leave to the compiler to drop not
called functions.
Yes. This looks better.
Thanks
Best regards,
baolu
