From: Michael Kelley <[email protected]> Sent: Thursday, May 14, 2026 11:14 AM > > From: Yu Zhang <[email protected]> Sent: Monday, May 11, 2026 9:24 > AM > > > > Add page-selective IOTLB flush using HVCALL_FLUSH_DEVICE_DOMAIN_LIST. > > This hypercall accepts a list of (page_number, page_mask_shift) entries, > > enabling finer-grained IOTLB invalidation compared to the domain-wide > > HVCALL_FLUSH_DEVICE_DOMAIN used by hv_iommu_flush_iotlb_all(). > > > > hv_iommu_fill_iova_list() decomposes a contiguous IOVA range into a > > minimal set of aligned power-of-two regions that fit in a single > > hypercall input page. When the range exceeds the page capacity, the > > code falls back to a full domain flush automatically. > > > > Signed-off-by: Yu Zhang <[email protected]> > > Signed-off-by: Easwar Hariharan <[email protected]> > > --- > > drivers/iommu/hyperv/iommu.c | 91 +++++++++++++++++++++++++++++++++++- > > include/hyperv/hvgdk_mini.h | 1 + > > include/hyperv/hvhdk_mini.h | 17 +++++++ > > 3 files changed, 108 insertions(+), 1 deletion(-) > > > > diff --git a/drivers/iommu/hyperv/iommu.c b/drivers/iommu/hyperv/iommu.c > > index e5fc625314b5..3bca362b7815 100644 > > --- a/drivers/iommu/hyperv/iommu.c > > +++ b/drivers/iommu/hyperv/iommu.c > > @@ -486,10 +486,98 @@ static void hv_iommu_flush_iotlb_all(struct > > iommu_domain *domain) > > hv_flush_device_domain(to_hv_iommu_domain(domain)); > > } > > > > +/* Max number of iova_list entries in a single hypercall input page. */ > > +#define HV_IOMMU_MAX_FLUSH_VA_COUNT \ > > + ((HV_HYP_PAGE_SIZE - sizeof(struct hv_input_flush_device_domain_list)) > > / \ > > + sizeof(union hv_iommu_flush_va)) > > + > > +/* Returned by hv_iommu_fill_iova_list() when the range exceeds the > > capacity */ > > +#define HV_IOMMU_FLUSH_VA_OVERFLOW U16_MAX > > + > > +static inline u16 hv_iommu_fill_iova_list(union hv_iommu_flush_va > > *iova_list, > > + unsigned long start, > > + unsigned long end) > > +{ > > + unsigned long start_pfn = start >> PAGE_SHIFT; > > + unsigned long end_pfn = PAGE_ALIGN(end) >> PAGE_SHIFT; > > "end" is an inclusive end address per comment in struct iommu_iotlb_gather. > So a page aligned value would typically have 0xFFF as the low order 12 bits, > and PAGE_ALIGN() will do the right thing. But I don't think the value is > *required* to be page aligned. If the value of "end" had 0x000 as the > low order 12 bits, the above calculation would fail to include the page > that has the address ending in 0x000. I think it needs to be > PAGE_ALIGN(end + 1) in order to work correctly for this corner case. >
One follow-on comment: the macros HVPFN_UP() and HVPFN_DOWN() would likely be useful in setting start_pfn and end_pfn. Michael
