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Message-ID: <20210120150011.dzzvzi6t4dvfy2w3@steredhat>
Date: Wed, 20 Jan 2021 16:00:11 +0100
From: Stefano Garzarella <sgarzare@...hat.com>
To: "Michael S. Tsirkin" <mst@...hat.com>,
virtualization@...ts.linux-foundation.org
Cc: Max Gurtovoy <mgurtovoy@...dia.com>,
Laurent Vivier <lvivier@...hat.com>,
"Michael S. Tsirkin" <mst@...hat.com>,
linux-kernel@...r.kernel.org, Jason Wang <jasowang@...hat.com>
Subject: Re: [PATCH v2] vdpa_sim: use iova module to allocate IOVA addresses
Hi Michael,
I'm restarting the work on vdpa-blk simulator, and this patch is needed
to have it working properly.
Do you plan to queue this patch or would you prefer that I include it in
my next vdpa-blk-sim series?
Thanks,
Stefano
On Wed, Dec 23, 2020 at 10:06:08AM +0100, 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 simplicity we use an IOVA allocator with byte granularity.
>
>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.
>
>Acked-by: Jason Wang <jasowang@...hat.com>
>Signed-off-by: Stefano Garzarella <sgarzare@...hat.com>
>---
>v2:
>- used ULONG_MAX instead of ~0UL [Jason]
>- fixed typos in comment and patch description [Jason]
>---
> 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..edc930719fb8 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 (ULONG_MAX - 1) */
>+ iova = alloc_iova(&vdpasim->iova, size, ULONG_MAX - 1, true);
>+ 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 simplicity we use an IOVA allocator with byte granularity */
>+ 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.
>--
>2.26.2
>
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