[PATCH] iommu/riscv: Report cache coherency capability
Andrew Jones <[email protected]>
| Newsgroups | org.infradead.lists.linux-riscv,dev.linux.lists.iommu,org.kernel.vger.linux-kernel |
|---|---|
| Message-ID | <[email protected]> |
VFIO and iommufd require IOMMU_CAP_CACHE_COHERENCY because they use IOMMU_CACHE mappings and have no userspace cache-maintenance path. RISC-V page tables preserve physical memory attributes for IOMMU_CACHE mappings. Svpbmt marks mappings without IOMMU_CACHE as non-cacheable, but preserving physical attributes cannot make a noncoherent device path coherent. Report the capability only for devices marked DMA coherent. This limits userspace assignment to paths that can honor cacheable mappings. Signed-off-by: Andrew Jones <[email protected]> Reviewed-by: Jason Gunthorpe <[email protected]> --- drivers/iommu/riscv/iommu.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/iommu/riscv/iommu.c b/drivers/iommu/riscv/iommu.c index 22cccc69bd2c..161093b1d9c5 100644 --- a/drivers/iommu/riscv/iommu.c +++ b/drivers/iommu/riscv/iommu.c @@ -16,6 +16,7 @@ #include <linux/acpi_rimt.h> #include <linux/compiler.h> #include <linux/crash_dump.h> +#include <linux/dma-map-ops.h> #include <linux/init.h> #include <linux/iommu.h> #include <linux/iopoll.h> @@ -1429,6 +1430,16 @@ static struct iommu_group *riscv_iommu_device_group(struct device *dev) return generic_device_group(dev); } +static bool riscv_iommu_capable(struct device *dev, enum iommu_cap cap) +{ + switch (cap) { + case IOMMU_CAP_CACHE_COHERENCY: + return dev_is_dma_coherent(dev); + default: + return false; + } +} + static int riscv_iommu_of_xlate(struct device *dev, const struct of_phandle_args *args) { return iommu_fwspec_add_ids(dev, args->args, 1); @@ -1520,6 +1531,7 @@ static void riscv_iommu_get_resv_regions(struct device *dev, struct list_head *h static const struct iommu_ops riscv_iommu_ops = { .of_xlate = riscv_iommu_of_xlate, + .capable = riscv_iommu_capable, .identity_domain = &riscv_iommu_identity_domain, .blocked_domain = &riscv_iommu_blocking_domain, .release_domain = &riscv_iommu_blocking_domain, -- 2.43.0 _______________________________________________ linux-riscv mailing list [email protected] http://lists.infradead.org/mailman/listinfo/linux-riscv