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 22E7B33D6E6 for ; Fri, 3 Apr 2026 05:11:55 +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=1775193117; cv=none; b=G69seUdG0Djl6QScidK4N24o/ueg3ly+LNuFv/9g8Y1HB5YhL4Q3rMAcl23H6mC8xMefXvvZSC/oB1+SnQp+zIb5zBadQQ/Q1eOtrdaXvew80rtlHjaiuAl6qP9+bXzB/LW4dtZ1lUBoDDiaXxBJjjQgBe0jGNjnfx6Thwab0V8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775193117; c=relaxed/simple; bh=KQ3WJU1tt1zFvb7kVMmh4hH+Z0AesLtbM2yhVBuAunw=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=Kfpn2QDxAiLHAR9FHDmQ7yt50OKBpdngdd5vUfWXZwlqGEpj/LWJhfH8IZucGA1a3s+EWaF7RkMNlWnwvQ7ZqdGqf6tmko9gdcRUu6LY9uAx7tsNZjst/76Pz4Xip89+/y+eE1y1r/lOKcXf2D+O3LayQTCuzipccxkgMacYaiM= 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=Gglb4NcP; 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="Gglb4NcP" Received: from DESKTOP-0403QTC.corp.microsoft.com (unknown [52.148.171.5]) by linux.microsoft.com (Postfix) with ESMTPSA id 2698920B7138; Thu, 2 Apr 2026 22:11:53 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 2698920B7138 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1775193113; bh=sIlQBLNxFlHKmin2kwEEybGlzkD3r2mL3/Ib5b7lBo0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Gglb4NcPKhDTzD9SfOPXUrmtDfIOsTv8AVrafohiFBoMBTPXqWJkjWTJrBKQur07L 3e+1LfHd43OA+RpeHoyMaJZpnA9EDsT6uqP+9xZ7pOe/ctDV0JhdVW4GydBax5KqOh KoxwgaEjAbd4G040XQetAwaPkso3tftW2gLefLqU= 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: skhawaja@google.com, pasha.tatashin@soleen.com, Will Deacon , Jacob Pan , Baolu Lu Subject: [PATCH V3 04/10] iommufd: Add an ioctl IOMMU_IOAS_GET_PA to query PA from IOVA Date: Thu, 2 Apr 2026 22:11:40 -0700 Message-Id: <20260403051146.10210-5-jacob.pan@linux.microsoft.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260403051146.10210-1-jacob.pan@linux.microsoft.com> References: <20260403051146.10210-1-jacob.pan@linux.microsoft.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 mock I/O page tables maintained by generic IOMMUPT framework. Suggested-by: Jason Gunthorpe Signed-off-by: Jacob Pan Signed-off-by: Jason Gunthorpe --- v2: - Scan the contiguous physical-address span beyond the first page and return its length. --- drivers/iommu/iommufd/io_pagetable.c | 60 +++++++++++++++++++++++++ drivers/iommu/iommufd/ioas.c | 25 +++++++++++ drivers/iommu/iommufd/iommufd_private.h | 3 ++ drivers/iommu/iommufd/main.c | 3 ++ include/uapi/linux/iommufd.h | 25 +++++++++++ 5 files changed, 116 insertions(+) diff --git a/drivers/iommu/iommufd/io_pagetable.c b/drivers/iommu/iommufd/io_pagetable.c index ee003bb2f647..5372fac6077b 100644 --- a/drivers/iommu/iommufd/io_pagetable.c +++ b/drivers/iommu/iommufd/io_pagetable.c @@ -849,6 +849,66 @@ int iopt_unmap_iova(struct io_pagetable *iopt, unsigned long iova, return iopt_unmap_iova_range(iopt, iova, iova_last, unmapped); } +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; + + if (!IS_ENABLED(CONFIG_VFIO_NOIOMMU)) + return -EOPNOTSUPP; + + 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; + 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; + + 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; +} + 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..93cebb4c23bd 100644 --- a/drivers/iommu/iommufd/ioas.c +++ b/drivers/iommu/iommufd/ioas.c @@ -375,6 +375,31 @@ int iommufd_ioas_unmap(struct iommufd_ucmd *ucmd) return rc; } +int iommufd_ioas_get_pa(struct iommufd_ucmd *ucmd) +{ + struct iommu_ioas_get_pa *cmd = ucmd->cmd; + struct iommufd_ioas *ioas; + int rc; + + 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; +} + 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 9c18c5eb1899..3302c6a1f99e 100644 --- a/drivers/iommu/iommufd/iommufd_private.h +++ b/drivers/iommu/iommufd/iommufd_private.h @@ -118,6 +118,8 @@ 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); +int iopt_get_phys(struct io_pagetable *iopt, unsigned long iova, u64 *paddr, + u64 *length); int iopt_read_and_clear_dirty_data(struct io_pagetable *iopt, struct iommu_domain *domain, @@ -346,6 +348,7 @@ 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); +int iommufd_ioas_get_pa(struct iommufd_ucmd *ucmd); 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..ebae01ed947d 100644 --- a/drivers/iommu/iommufd/main.c +++ b/drivers/iommu/iommufd/main.c @@ -432,6 +432,7 @@ union ucmd_buffer { struct iommu_veventq_alloc veventq; struct iommu_vfio_ioas vfio_ioas; struct iommu_viommu_alloc viommu; + struct iommu_ioas_get_pa get_pa; #ifdef CONFIG_IOMMUFD_TEST struct iommu_test_cmd test; #endif @@ -484,6 +485,8 @@ static const struct iommufd_ioctl_op iommufd_ioctl_ops[] = { struct iommu_ioas_map_file, iova), IOCTL_OP(IOMMU_IOAS_UNMAP, iommufd_ioas_unmap, struct iommu_ioas_unmap, length), + IOCTL_OP(IOMMU_IOAS_GET_PA, iommufd_ioas_get_pa, struct iommu_ioas_get_pa, + out_phys), IOCTL_OP(IOMMU_OPTION, iommufd_option, struct iommu_option, val64), IOCTL_OP(IOMMU_VDEVICE_ALLOC, iommufd_vdevice_alloc_ioctl, struct iommu_vdevice_alloc, virt_id), diff --git a/include/uapi/linux/iommufd.h b/include/uapi/linux/iommufd.h index 1dafbc552d37..9afe0a1b11a0 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_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_get_pa - ioctl(IOMMU_IOAS_GET_PA) + * @size: sizeof(struct iommu_ioas_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_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_GET_PA _IO(IOMMUFD_TYPE, IOMMUFD_CMD_IOAS_GET_PA) + /** * struct iommu_ioas_map_file - ioctl(IOMMU_IOAS_MAP_FILE) * @size: sizeof(struct iommu_ioas_map_file) -- 2.34.1