On Thu, Feb 08, 2024 at 02:16:50AM +0530, ankita@xxxxxxxxxx wrote: > diff --git a/include/linux/mm.h b/include/linux/mm.h > index f5a97dec5169..884c068a79eb 100644 > --- a/include/linux/mm.h > +++ b/include/linux/mm.h > @@ -391,6 +391,20 @@ extern unsigned int kobjsize(const void *objp); > # define VM_UFFD_MINOR VM_NONE > #endif /* CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */ > > +/* > + * This flag is used to connect VFIO to arch specific KVM code. It > + * indicates that the memory under this VMA is safe for use with any > + * non-cachable memory type inside KVM. Some VFIO devices, on some > + * platforms, are thought to be unsafe and can cause machine crashes if > + * KVM does not lock down the memory type. > + */ > +#ifdef CONFIG_64BIT > +#define VM_VFIO_ALLOW_WC_BIT 39 > +#define VM_VFIO_ALLOW_WC BIT(VM_VFIO_ALLOW_WC_BIT) > +#else > +#define VM_VFIO_ALLOW_WC VM_NONE > +#endif Adding David Hildenbrand to this thread as well since we briefly discussed potential alternatives (not sure we came to any conclusion). -- Catalin
