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Date: Wed, 23 Dec 2020 08:53:05 +0100
From: Stefano Garzarella <sgarzare@...hat.com>
To: Jason Wang <jasowang@...hat.com>
Cc: virtualization@...ts.linux-foundation.org,
linux-kernel@...r.kernel.org, Max Gurtovoy <mgurtovoy@...dia.com>,
Laurent Vivier <lvivier@...hat.com>,
"Michael S. Tsirkin" <mst@...hat.com>
Subject: Re: [PATCH] vdpa_sim: use iova module to allocate IOVA addresses
On Wed, Dec 23, 2020 at 11:43:40AM +0800, Jason Wang wrote:
>
>On 2020/12/23 上午1:45, Stefano Garzarella wrote:
>>The identical mapping used until now created issues when mapping
>>different virtual pages with the same physical address.
>>To solve this issue, we can use the iova module, to handle the IOVA
>>allocation.
>>For semplicity we use an IOVA allocator with byte granularity.
>
>
>Should be simplicity, so did one comment below.
Right, I'll fix here and in the comment below.
>
>
>>
>>We add two new functions, vdpasim_map_range() and vdpasim_unmap_range(),
>>to handle the IOVA allocation and the registration into the IOMMU/IOTLB.
>>These functions are used by dma_map_ops callbacks.
>>
>>Signed-off-by: Stefano Garzarella <sgarzare@...hat.com>
>
>
>Few nits, but:
>
>Acked-by: Jason Wang <jasowang@...hat.com>
Thanks!
>
>
>>---
>> drivers/vdpa/vdpa_sim/vdpa_sim.h | 2 +
>> drivers/vdpa/vdpa_sim/vdpa_sim.c | 108 +++++++++++++++++++------------
>> drivers/vdpa/Kconfig | 1 +
>> 3 files changed, 69 insertions(+), 42 deletions(-)
>>
>>diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.h b/drivers/vdpa/vdpa_sim/vdpa_sim.h
>>index b02142293d5b..6efe205e583e 100644
>>--- a/drivers/vdpa/vdpa_sim/vdpa_sim.h
>>+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.h
>>@@ -6,6 +6,7 @@
>> #ifndef _VDPA_SIM_H
>> #define _VDPA_SIM_H
>>+#include <linux/iova.h>
>> #include <linux/vringh.h>
>> #include <linux/vdpa.h>
>> #include <linux/virtio_byteorder.h>
>>@@ -55,6 +56,7 @@ struct vdpasim {
>> /* virtio config according to device type */
>> void *config;
>> struct vhost_iotlb *iommu;
>>+ struct iova_domain iova;
>> void *buffer;
>> u32 status;
>> u32 generation;
>>diff --git a/drivers/vdpa/vdpa_sim/vdpa_sim.c b/drivers/vdpa/vdpa_sim/vdpa_sim.c
>>index b3fcc67bfdf0..341b9daf2ea4 100644
>>--- a/drivers/vdpa/vdpa_sim/vdpa_sim.c
>>+++ b/drivers/vdpa/vdpa_sim/vdpa_sim.c
>>@@ -17,6 +17,7 @@
>> #include <linux/vringh.h>
>> #include <linux/vdpa.h>
>> #include <linux/vhost_iotlb.h>
>>+#include <linux/iova.h>
>> #include "vdpa_sim.h"
>>@@ -128,30 +129,57 @@ static int dir_to_perm(enum dma_data_direction dir)
>> return perm;
>> }
>>+static dma_addr_t vdpasim_map_range(struct vdpasim *vdpasim, phys_addr_t paddr,
>>+ size_t size, unsigned int perm)
>>+{
>>+ struct iova *iova;
>>+ dma_addr_t dma_addr;
>>+ int ret;
>>+
>>+ /* We set the limit_pfn to the maximum (~0UL - 1) */
>>+ iova = alloc_iova(&vdpasim->iova, size, ~0UL - 1, true);
>
>
>Let's use ULONG_MAX?
Definitely, much better!
>
>
>>+ if (!iova)
>>+ return DMA_MAPPING_ERROR;
>>+
>>+ dma_addr = iova_dma_addr(&vdpasim->iova, iova);
>>+
>>+ spin_lock(&vdpasim->iommu_lock);
>>+ ret = vhost_iotlb_add_range(vdpasim->iommu, (u64)dma_addr,
>>+ (u64)dma_addr + size - 1, (u64)paddr, perm);
>>+ spin_unlock(&vdpasim->iommu_lock);
>>+
>>+ if (ret) {
>>+ __free_iova(&vdpasim->iova, iova);
>>+ return DMA_MAPPING_ERROR;
>>+ }
>>+
>>+ return dma_addr;
>>+}
>>+
>>+static void vdpasim_unmap_range(struct vdpasim *vdpasim, dma_addr_t dma_addr,
>>+ size_t size)
>>+{
>>+ spin_lock(&vdpasim->iommu_lock);
>>+ vhost_iotlb_del_range(vdpasim->iommu, (u64)dma_addr,
>>+ (u64)dma_addr + size - 1);
>>+ spin_unlock(&vdpasim->iommu_lock);
>>+
>>+ free_iova(&vdpasim->iova, iova_pfn(&vdpasim->iova, dma_addr));
>>+}
>>+
>> static dma_addr_t vdpasim_map_page(struct device *dev, struct page *page,
>> unsigned long offset, size_t size,
>> enum dma_data_direction dir,
>> unsigned long attrs)
>> {
>> struct vdpasim *vdpasim = dev_to_sim(dev);
>>- struct vhost_iotlb *iommu = vdpasim->iommu;
>>- u64 pa = (page_to_pfn(page) << PAGE_SHIFT) + offset;
>>- int ret, perm = dir_to_perm(dir);
>>+ phys_addr_t paddr = page_to_phys(page) + offset;
>>+ int perm = dir_to_perm(dir);
>> if (perm < 0)
>> return DMA_MAPPING_ERROR;
>>- /* For simplicity, use identical mapping to avoid e.g iova
>>- * allocator.
>>- */
>>- spin_lock(&vdpasim->iommu_lock);
>>- ret = vhost_iotlb_add_range(iommu, pa, pa + size - 1,
>>- pa, dir_to_perm(dir));
>>- spin_unlock(&vdpasim->iommu_lock);
>>- if (ret)
>>- return DMA_MAPPING_ERROR;
>>-
>>- return (dma_addr_t)(pa);
>>+ return vdpasim_map_range(vdpasim, paddr, size, perm);
>> }
>> static void vdpasim_unmap_page(struct device *dev, dma_addr_t dma_addr,
>>@@ -159,12 +187,8 @@ static void vdpasim_unmap_page(struct device *dev, dma_addr_t dma_addr,
>> unsigned long attrs)
>> {
>> struct vdpasim *vdpasim = dev_to_sim(dev);
>>- struct vhost_iotlb *iommu = vdpasim->iommu;
>>- spin_lock(&vdpasim->iommu_lock);
>>- vhost_iotlb_del_range(iommu, (u64)dma_addr,
>>- (u64)dma_addr + size - 1);
>>- spin_unlock(&vdpasim->iommu_lock);
>>+ vdpasim_unmap_range(vdpasim, dma_addr, size);
>> }
>> static void *vdpasim_alloc_coherent(struct device *dev, size_t size,
>>@@ -172,27 +196,22 @@ static void *vdpasim_alloc_coherent(struct device *dev, size_t size,
>> unsigned long attrs)
>> {
>> struct vdpasim *vdpasim = dev_to_sim(dev);
>>- struct vhost_iotlb *iommu = vdpasim->iommu;
>>- void *addr = kmalloc(size, flag);
>>- int ret;
>>+ phys_addr_t paddr;
>>+ void *addr;
>>- spin_lock(&vdpasim->iommu_lock);
>>+ addr = kmalloc(size, flag);
>> if (!addr) {
>> *dma_addr = DMA_MAPPING_ERROR;
>>- } else {
>>- u64 pa = virt_to_phys(addr);
>>-
>>- ret = vhost_iotlb_add_range(iommu, (u64)pa,
>>- (u64)pa + size - 1,
>>- pa, VHOST_MAP_RW);
>>- if (ret) {
>>- *dma_addr = DMA_MAPPING_ERROR;
>>- kfree(addr);
>>- addr = NULL;
>>- } else
>>- *dma_addr = (dma_addr_t)pa;
>>+ return NULL;
>>+ }
>>+
>>+ paddr = virt_to_phys(addr);
>>+
>>+ *dma_addr = vdpasim_map_range(vdpasim, paddr, size, VHOST_MAP_RW);
>>+ if (*dma_addr == DMA_MAPPING_ERROR) {
>>+ kfree(addr);
>>+ return NULL;
>> }
>>- spin_unlock(&vdpasim->iommu_lock);
>> return addr;
>> }
>>@@ -202,14 +221,10 @@ static void vdpasim_free_coherent(struct device *dev, size_t size,
>> unsigned long attrs)
>> {
>> struct vdpasim *vdpasim = dev_to_sim(dev);
>>- struct vhost_iotlb *iommu = vdpasim->iommu;
>>- spin_lock(&vdpasim->iommu_lock);
>>- vhost_iotlb_del_range(iommu, (u64)dma_addr,
>>- (u64)dma_addr + size - 1);
>>- spin_unlock(&vdpasim->iommu_lock);
>>+ vdpasim_unmap_range(vdpasim, dma_addr, size);
>>- kfree(phys_to_virt((uintptr_t)dma_addr));
>>+ kfree(vaddr);
>> }
>> static const struct dma_map_ops vdpasim_dma_ops = {
>>@@ -270,6 +285,13 @@ struct vdpasim *vdpasim_create(struct vdpasim_dev_attr *dev_attr)
>> for (i = 0; i < dev_attr->nvqs; i++)
>> vringh_set_iotlb(&vdpasim->vqs[i].vring, vdpasim->iommu);
>>+ ret = iova_cache_get();
>>+ if (ret)
>>+ goto err_iommu;
>>+
>>+ /* For semplicity we use an IOVA allocator with byte granularity */
>
>
>Should be simplicity.
Fixed :-)
Thanks,
Stefano
>
>Thanks
>
>
>>+ init_iova_domain(&vdpasim->iova, 1, 0);
>>+
>> vdpasim->vdpa.dma_dev = dev;
>> return vdpasim;
>>@@ -540,6 +562,8 @@ static void vdpasim_free(struct vdpa_device *vdpa)
>> struct vdpasim *vdpasim = vdpa_to_sim(vdpa);
>> cancel_work_sync(&vdpasim->work);
>>+ put_iova_domain(&vdpasim->iova);
>>+ iova_cache_put();
>> kvfree(vdpasim->buffer);
>> if (vdpasim->iommu)
>> vhost_iotlb_free(vdpasim->iommu);
>>diff --git a/drivers/vdpa/Kconfig b/drivers/vdpa/Kconfig
>>index 92a6396f8a73..8965e3717231 100644
>>--- a/drivers/vdpa/Kconfig
>>+++ b/drivers/vdpa/Kconfig
>>@@ -13,6 +13,7 @@ config VDPA_SIM
>> depends on RUNTIME_TESTING_MENU && HAS_DMA
>> select DMA_OPS
>> select VHOST_RING
>>+ select IOMMU_IOVA
>> help
>> Enable this module to support vDPA device simulators. These devices
>> are used for testing, prototyping and development of vDPA.
>
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