From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 940243A1D05 for ; Mon, 11 May 2026 18:58:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=13.77.154.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778525912; cv=none; b=Ur8AdYQzQEZ1isyPhwnOxrpYPF/zYqneFzKLtybotR63qeCVZTinhnDDW/S6wTgx05+yb5QWP/K2DkavKH3DXDBgp2ucpEKXIsOfCL0fE/ZoS68KbAhhWEVj76pbqh6/jPW200199jijnJ08qnzN2Qn4seRbzIIp36RQyZVej+w= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778525912; c=relaxed/simple; bh=A/clRb62DgThFELba4Nzy9mldvjJirjuzPTOv0Lwn8Y=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=pUuYle2MdDsqpgke9W2LCY/Ge4rhWWPSKZjuR5rKEFGkO5ZmWj5gK9d1FbiPGvtIQooviD46oZLRJir2zZIxoljEwRnCugU2XIlNwJJn0oqRG3gKGUlWHWpRiOWF2Ee6x9aJkXD7gry1+ypqB/Uzxe02HNCoYG7quIV9vECINIQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com; spf=pass smtp.mailfrom=linux.microsoft.com; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b=fno7gxV3; arc=none smtp.client-ip=13.77.154.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.microsoft.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.microsoft.com header.i=@linux.microsoft.com header.b="fno7gxV3" Received: from localhost (unknown [52.148.140.42]) by linux.microsoft.com (Postfix) with ESMTPSA id 681B620B7166; Mon, 11 May 2026 11:58:26 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 681B620B7166 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1778525907; bh=BuRk1dSRJNA3nK7dDJqVqlAyDvosvvfcLRr5megxS8I=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=fno7gxV3ReS9jc+70A8wjXwk1q7rXP/YHJElzIapl/FruaChXEMK3oxkXldu+mzV2 kZUk3hpCCLIobKMSYShbKVt350T1YjSdFT/628QGnweoPdfDFhUrGR2E6AREKalps6 UslcsyIsZ4ts+KBKGAegwgm7Wp20WvmcdulwNi1M= Date: Mon, 11 May 2026 11:58:26 -0700 From: Jacob Pan To: linux-kernel@vger.kernel.org, "iommu@lists.linux.dev" , Jason Gunthorpe , Alex Williamson , Joerg Roedel , Mostafa Saleh , David Matlack , Robin Murphy , Nicolin Chen , "Tian, Kevin" , Yi Liu Cc: Saurabh Sengar , skhawaja@google.com, pasha.tatashin@soleen.com, Will Deacon , Baolu Lu , jacob.pan@linux.microsoft.com Subject: Re: [PATCH v5 5/9] iommufd: Add an ioctl to query PA from IOVA for noiommu mode Message-ID: <20260511115826.00000f6d@linux.microsoft.com> In-Reply-To: <20260511184116.3687392-6-jacob.pan@linux.microsoft.com> References: <20260511184116.3687392-1-jacob.pan@linux.microsoft.com> <20260511184116.3687392-6-jacob.pan@linux.microsoft.com> Organization: LSG X-Mailer: Claws Mail 3.21.0 (GTK+ 2.24.33; x86_64-w64-mingw32) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Mon, 11 May 2026 11:41:10 -0700 Jacob Pan wrote: > To support no-IOMMU mode where userspace drivers perform unsafe DMA > using physical addresses, introduce a new API to retrieve the > physical address of a user-allocated DMA buffer that has been mapped > to an IOVA via IOAS. The mapping is backed by SW-only I/O page tables > maintained by the generic IOMMUPT framework. > > Suggested-by: Jason Gunthorpe > Signed-off-by: Jason Gunthorpe > Signed-off-by: Jacob Pan > --- > v5: > - Add header stubs for iopt_get_phys() and > iommufd_ioas_noiommu_get_pa() to avoid ifdef at call sites > (Kevin) v4: > - Fix ioctl return type (Yi Liu) This is not the correct change log, I have made a mistake. The correct one should be: - Fix next_iova exceeds iopt_area_last_iova (Alex) - Rename IOCTL more specific to NOIOMMU, i.e. IOMMUFD_CMD_IOAS_NOIOMMU_GET_PA (Kevin) Sorry about that. > v2: > - New patch > --- > drivers/iommu/iommufd/io_pagetable.c | 62 > +++++++++++++++++++++++++ drivers/iommu/iommufd/ioas.c | > 30 ++++++++++++ drivers/iommu/iommufd/iommufd_private.h | 18 +++++++ > drivers/iommu/iommufd/main.c | 3 ++ > include/uapi/linux/iommufd.h | 25 ++++++++++ > 5 files changed, 138 insertions(+) > > diff --git a/drivers/iommu/iommufd/io_pagetable.c > b/drivers/iommu/iommufd/io_pagetable.c index > 24d4917105d9..1ee7c8e6408c 100644 --- > a/drivers/iommu/iommufd/io_pagetable.c +++ > b/drivers/iommu/iommufd/io_pagetable.c @@ -859,6 +859,68 @@ int > iopt_unmap_iova(struct io_pagetable *iopt, unsigned long iova, return > iopt_unmap_iova_range(iopt, iova, iova_last, unmapped); } > > +#ifdef CONFIG_IOMMUFD_NOIOMMU > +int iopt_get_phys(struct io_pagetable *iopt, unsigned long iova, u64 > *paddr, > + u64 *length) > +{ > + struct iopt_area *area; > + u64 tmp_length = 0; > + u64 tmp_paddr = 0; > + int rc = 0; > + > + down_read(&iopt->iova_rwsem); > + area = iopt_area_iter_first(iopt, iova, iova); > + if (!area || !area->pages) { > + rc = -ENOENT; > + goto unlock_exit; > + } > + > + if (!area->storage_domain || > + area->storage_domain->owner != &iommufd_noiommu_ops) { > + rc = -EOPNOTSUPP; > + goto unlock_exit; > + } > + > + *paddr = iommu_iova_to_phys(area->storage_domain, iova); > + if (!*paddr) { > + rc = -EINVAL; > + goto unlock_exit; > + } > + > + tmp_length = PAGE_SIZE - offset_in_page(iova); > + tmp_paddr = *paddr; > + /* > + * Scan the domain for the contiguous physical address > length so that > + * userspace search can be optimized for fewer ioctls. > + */ > + while (iova < iopt_area_last_iova(area)) { > + unsigned long next_iova; > + u64 next_paddr; > + > + if (check_add_overflow(iova, PAGE_SIZE, &next_iova)) > + break; > + > + if (next_iova > iopt_area_last_iova(area)) > + break; > + > + next_paddr = > iommu_iova_to_phys(area->storage_domain, next_iova); + > + if (!next_paddr || next_paddr != tmp_paddr + > PAGE_SIZE) > + break; > + > + iova = next_iova; > + tmp_paddr += PAGE_SIZE; > + tmp_length += PAGE_SIZE; > + } > + *length = tmp_length; > + > +unlock_exit: > + up_read(&iopt->iova_rwsem); > + > + return rc; > +} > +#endif > + > int iopt_unmap_all(struct io_pagetable *iopt, unsigned long > *unmapped) { > /* If the IOVAs are empty then unmap all succeeds */ > diff --git a/drivers/iommu/iommufd/ioas.c > b/drivers/iommu/iommufd/ioas.c index fed06c2b728e..666440e32c9e 100644 > --- a/drivers/iommu/iommufd/ioas.c > +++ b/drivers/iommu/iommufd/ioas.c > @@ -375,6 +375,36 @@ int iommufd_ioas_unmap(struct iommufd_ucmd *ucmd) > return rc; > } > > +#ifdef CONFIG_IOMMUFD_NOIOMMU > +int iommufd_ioas_noiommu_get_pa(struct iommufd_ucmd *ucmd) > +{ > + struct iommu_ioas_noiommu_get_pa *cmd = ucmd->cmd; > + struct iommufd_ioas *ioas; > + int rc; > + > + if (!capable(CAP_SYS_RAWIO)) > + return -EPERM; > + > + if (cmd->flags || cmd->__reserved) > + return -EOPNOTSUPP; > + > + ioas = iommufd_get_ioas(ucmd->ictx, cmd->ioas_id); > + if (IS_ERR(ioas)) > + return PTR_ERR(ioas); > + > + rc = iopt_get_phys(&ioas->iopt, cmd->iova, &cmd->out_phys, > + &cmd->out_length); > + if (rc) > + goto out_put; > + > + rc = iommufd_ucmd_respond(ucmd, sizeof(*cmd)); > +out_put: > + iommufd_put_object(ucmd->ictx, &ioas->obj); > + > + return rc; > +} > +#endif > + > static void iommufd_release_all_iova_rwsem(struct iommufd_ctx *ictx, > struct xarray *ioas_list) > { > diff --git a/drivers/iommu/iommufd/iommufd_private.h > b/drivers/iommu/iommufd/iommufd_private.h index > 2682b5baa6e9..13f1506d8066 100644 --- > a/drivers/iommu/iommufd/iommufd_private.h +++ > b/drivers/iommu/iommufd/iommufd_private.h @@ -118,6 +118,16 @@ int > iopt_map_pages(struct io_pagetable *iopt, struct list_head > *pages_list, int iopt_unmap_iova(struct io_pagetable *iopt, unsigned > long iova, unsigned long length, unsigned long *unmapped); int > iopt_unmap_all(struct io_pagetable *iopt, unsigned long *unmapped); > +#ifdef CONFIG_IOMMUFD_NOIOMMU +int iopt_get_phys(struct io_pagetable > *iopt, unsigned long iova, u64 *paddr, > + u64 *length); > +#else > +static inline int iopt_get_phys(struct io_pagetable *iopt, unsigned > long iova, > + u64 *paddr, u64 *length) > +{ > + return -EOPNOTSUPP; > +} > +#endif > > int iopt_read_and_clear_dirty_data(struct io_pagetable *iopt, > struct iommu_domain *domain, > @@ -346,6 +356,14 @@ int iommufd_ioas_map_file(struct iommufd_ucmd > *ucmd); int iommufd_ioas_change_process(struct iommufd_ucmd *ucmd); > int iommufd_ioas_copy(struct iommufd_ucmd *ucmd); > int iommufd_ioas_unmap(struct iommufd_ucmd *ucmd); > +#ifdef CONFIG_IOMMUFD_NOIOMMU > +int iommufd_ioas_noiommu_get_pa(struct iommufd_ucmd *ucmd); > +#else > +static inline int iommufd_ioas_noiommu_get_pa(struct iommufd_ucmd > *ucmd) +{ > + return -EOPNOTSUPP; > +} > +#endif > int iommufd_ioas_option(struct iommufd_ucmd *ucmd); > int iommufd_option_rlimit_mode(struct iommu_option *cmd, > struct iommufd_ctx *ictx); > diff --git a/drivers/iommu/iommufd/main.c > b/drivers/iommu/iommufd/main.c index 8c6d43601afb..3b4192d70570 100644 > --- a/drivers/iommu/iommufd/main.c > +++ b/drivers/iommu/iommufd/main.c > @@ -424,6 +424,7 @@ union ucmd_buffer { > struct iommu_ioas_alloc alloc; > struct iommu_ioas_allow_iovas allow_iovas; > struct iommu_ioas_copy ioas_copy; > + struct iommu_ioas_noiommu_get_pa noiommu_get_pa; > struct iommu_ioas_iova_ranges iova_ranges; > struct iommu_ioas_map map; > struct iommu_ioas_unmap unmap; > @@ -482,6 +483,8 @@ static const struct iommufd_ioctl_op > iommufd_ioctl_ops[] = { IOCTL_OP(IOMMU_IOAS_MAP, iommufd_ioas_map, > struct iommu_ioas_map, iova), IOCTL_OP(IOMMU_IOAS_MAP_FILE, > iommufd_ioas_map_file, struct iommu_ioas_map_file, iova), > + IOCTL_OP(IOMMU_IOAS_NOIOMMU_GET_PA, > iommufd_ioas_noiommu_get_pa, struct iommu_ioas_noiommu_get_pa, > + out_phys), > IOCTL_OP(IOMMU_IOAS_UNMAP, iommufd_ioas_unmap, struct > iommu_ioas_unmap, length), > IOCTL_OP(IOMMU_OPTION, iommufd_option, struct iommu_option, > val64), diff --git a/include/uapi/linux/iommufd.h > b/include/uapi/linux/iommufd.h index e998dfbd6960..7df366d161f1 100644 > --- a/include/uapi/linux/iommufd.h > +++ b/include/uapi/linux/iommufd.h > @@ -57,6 +57,7 @@ enum { > IOMMUFD_CMD_IOAS_CHANGE_PROCESS = 0x92, > IOMMUFD_CMD_VEVENTQ_ALLOC = 0x93, > IOMMUFD_CMD_HW_QUEUE_ALLOC = 0x94, > + IOMMUFD_CMD_IOAS_NOIOMMU_GET_PA = 0x95, > }; > > /** > @@ -219,6 +220,30 @@ struct iommu_ioas_map { > }; > #define IOMMU_IOAS_MAP _IO(IOMMUFD_TYPE, IOMMUFD_CMD_IOAS_MAP) > > +/** > + * struct iommu_ioas_noiommu_get_pa - > ioctl(IOMMU_IOAS_NOIOMMU_GET_PA) > + * @size: sizeof(struct iommu_ioas_noiommu_get_pa) > + * @flags: Reserved, must be 0 for now > + * @ioas_id: IOAS ID to query IOVA to PA mapping from > + * @__reserved: Must be 0 > + * @iova: IOVA to query > + * @out_length: Number of bytes contiguous physical address starting > from phys > + * @out_phys: Output physical address the IOVA maps to > + * > + * Query the physical address backing an IOVA range. The entire > range must be > + * mapped already. For noiommu devices doing unsafe DMA only. > + */ > +struct iommu_ioas_noiommu_get_pa { > + __u32 size; > + __u32 flags; > + __u32 ioas_id; > + __u32 __reserved; > + __aligned_u64 iova; > + __aligned_u64 out_length; > + __aligned_u64 out_phys; > +}; > +#define IOMMU_IOAS_NOIOMMU_GET_PA _IO(IOMMUFD_TYPE, > IOMMUFD_CMD_IOAS_NOIOMMU_GET_PA) + > /** > * struct iommu_ioas_map_file - ioctl(IOMMU_IOAS_MAP_FILE) > * @size: sizeof(struct iommu_ioas_map_file)