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([2a01:e0a:59e:9d80:527b:9dff:feef:3874]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-438b31d9a39sm67975795e9.31.2025.01.23.09.10.47 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 23 Jan 2025 09:10:50 -0800 (PST) Message-ID: <787fd89b-fbc0-4fd5-a1af-63dfddf13435@redhat.com> Date: Thu, 23 Jan 2025 18:10:47 +0100 Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Reply-To: eric.auger@redhat.com Subject: Re: [PATCH RFCv2 03/13] iommu: Make iommu_dma_prepare_msi() into a generic operation Content-Language: en-US To: Nicolin Chen , will@kernel.org, robin.murphy@arm.com, jgg@nvidia.com, kevin.tian@intel.com, tglx@linutronix.de, maz@kernel.org, alex.williamson@redhat.com Cc: joro@8bytes.org, shuah@kernel.org, reinette.chatre@intel.com, yebin10@huawei.com, apatel@ventanamicro.com, shivamurthy.shastri@linutronix.de, bhelgaas@google.com, anna-maria@linutronix.de, yury.norov@gmail.com, nipun.gupta@amd.com, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, patches@lists.linux.dev, jean-philippe@linaro.org, mdf@kernel.org, mshavit@google.com, shameerali.kolothum.thodi@huawei.com, smostafa@google.com, ddutile@redhat.com References: <9914f9e6b32d49f74ace2200fd50583def9f15f6.1736550979.git.nicolinc@nvidia.com> From: Eric Auger In-Reply-To: <9914f9e6b32d49f74ace2200fd50583def9f15f6.1736550979.git.nicolinc@nvidia.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Hi, On 1/11/25 4:32 AM, Nicolin Chen wrote: > From: Jason Gunthorpe > > SW_MSI supports IOMMU to translate an MSI message before the MSI message > is delivered to the interrupt controller. On such systems the iommu_domain > must have a translation for the MSI message for interrupts to work. > > The IRQ subsystem will call into IOMMU to request that a physical page be > setup to receive MSI message, and the IOMMU then sets an IOVA that maps to > that physical page. Ultimately the IOVA is programmed into the device via > the msi_msg. > > Generalize this to allow the iommu_domain owner to provide its own > implementation of this mapping. Add a function pointer to struct > iommu_domain to allow the domain owner to provide an implementation. > > Have dma-iommu supply its implementation for IOMMU_DOMAIN_DMA types during > the iommu_get_dma_cookie() path. For IOMMU_DOMAIN_UNMANAGED types used by > VFIO (and iommufd for now), have the same iommu_dma_sw_msi set as well in > the iommu_get_msi_cookie() path. > > Hold the group mutex while in iommu_dma_prepare_msi() to ensure the domain > doesn't change or become freed while running. Races with IRQ operations > from VFIO and domain changes from iommufd are possible here. this was my question in previous comments > > Rreplace the msi_prepare_lock with a lockdep assertion for the group mutex Replace > as documentation. For the dma_iommu.c each iommu_domain unique to a is? > group. > > Signed-off-by: Jason Gunthorpe > [nicolinc: move iommu_domain_set_sw_msi() from iommu_dma_init_domain() to > iommu_dma_init_domain(); add in iommu_put_dma_cookie() an sw_msi test] > Signed-off-by: Nicolin Chen > --- > include/linux/iommu.h | 44 ++++++++++++++++++++++++++------------- > drivers/iommu/dma-iommu.c | 33 +++++++++++++---------------- > drivers/iommu/iommu.c | 29 ++++++++++++++++++++++++++ > 3 files changed, 73 insertions(+), 33 deletions(-) > > diff --git a/include/linux/iommu.h b/include/linux/iommu.h > index 3a4215966c1b..423fdfa6b3bb 100644 > --- a/include/linux/iommu.h > +++ b/include/linux/iommu.h > @@ -44,6 +44,8 @@ struct iommu_dma_cookie; > struct iommu_fault_param; > struct iommufd_ctx; > struct iommufd_viommu; > +struct msi_desc; > +struct msi_msg; > > #define IOMMU_FAULT_PERM_READ (1 << 0) /* read */ > #define IOMMU_FAULT_PERM_WRITE (1 << 1) /* write */ > @@ -216,6 +218,12 @@ struct iommu_domain { > struct iommu_domain_geometry geometry; > struct iommu_dma_cookie *iova_cookie; > int (*iopf_handler)(struct iopf_group *group); > + > +#if IS_ENABLED(CONFIG_IRQ_MSI_IOMMU) > + int (*sw_msi)(struct iommu_domain *domain, struct msi_desc *desc, > + phys_addr_t msi_addr); > +#endif > + > void *fault_data; > union { > struct { > @@ -234,6 +242,16 @@ struct iommu_domain { > }; > }; > > +static inline void iommu_domain_set_sw_msi( > + struct iommu_domain *domain, > + int (*sw_msi)(struct iommu_domain *domain, struct msi_desc *desc, > + phys_addr_t msi_addr)) > +{ > +#if IS_ENABLED(CONFIG_IRQ_MSI_IOMMU) > + domain->sw_msi = sw_msi; > +#endif > +} > + > static inline bool iommu_is_dma_domain(struct iommu_domain *domain) > { > return domain->type & __IOMMU_DOMAIN_DMA_API; > @@ -1475,6 +1493,18 @@ static inline ioasid_t iommu_alloc_global_pasid(struct device *dev) > static inline void iommu_free_global_pasid(ioasid_t pasid) {} > #endif /* CONFIG_IOMMU_API */ > > +#ifdef CONFIG_IRQ_MSI_IOMMU > +#ifdef CONFIG_IOMMU_API > +int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr); > +#else > +static inline int iommu_dma_prepare_msi(struct msi_desc *desc, > + phys_addr_t msi_addr) > +{ > + return 0; > +} > +#endif /* CONFIG_IOMMU_API */ > +#endif /* CONFIG_IRQ_MSI_IOMMU */ > + > #if IS_ENABLED(CONFIG_LOCKDEP) && IS_ENABLED(CONFIG_IOMMU_API) > void iommu_group_mutex_assert(struct device *dev); > #else > @@ -1508,26 +1538,12 @@ static inline void iommu_debugfs_setup(void) {} > #endif > > #ifdef CONFIG_IOMMU_DMA > -#include > - > int iommu_get_msi_cookie(struct iommu_domain *domain, dma_addr_t base); > - > -int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr); > - > #else /* CONFIG_IOMMU_DMA */ > - > -struct msi_desc; > -struct msi_msg; > - > static inline int iommu_get_msi_cookie(struct iommu_domain *domain, dma_addr_t base) > { > return -ENODEV; > } > - > -static inline int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr) > -{ > - return 0; > -} > #endif /* CONFIG_IOMMU_DMA */ > > /* > diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c > index bf91e014d179..3b58244e6344 100644 > --- a/drivers/iommu/dma-iommu.c > +++ b/drivers/iommu/dma-iommu.c > @@ -24,6 +24,7 @@ > #include > #include > #include > +#include > #include > #include > #include > @@ -102,6 +103,9 @@ static int __init iommu_dma_forcedac_setup(char *str) > } > early_param("iommu.forcedac", iommu_dma_forcedac_setup); > > +static int iommu_dma_sw_msi(struct iommu_domain *domain, struct msi_desc *desc, > + phys_addr_t msi_addr); > + > /* Number of entries per flush queue */ > #define IOVA_DEFAULT_FQ_SIZE 256 > #define IOVA_SINGLE_FQ_SIZE 32768 > @@ -398,6 +402,7 @@ int iommu_get_dma_cookie(struct iommu_domain *domain) > return -ENOMEM; > > mutex_init(&domain->iova_cookie->mutex); > + iommu_domain_set_sw_msi(domain, iommu_dma_sw_msi); > return 0; > } > > @@ -429,6 +434,7 @@ int iommu_get_msi_cookie(struct iommu_domain *domain, dma_addr_t base) > > cookie->msi_iova = base; > domain->iova_cookie = cookie; > + iommu_domain_set_sw_msi(domain, iommu_dma_sw_msi); > return 0; > } > EXPORT_SYMBOL(iommu_get_msi_cookie); > @@ -443,6 +449,9 @@ void iommu_put_dma_cookie(struct iommu_domain *domain) > struct iommu_dma_cookie *cookie = domain->iova_cookie; > struct iommu_dma_msi_page *msi, *tmp; > > + if (domain->sw_msi != iommu_dma_sw_msi) > + return; > + I don't get the above check. The comment says this is also called for a cookie prepared with iommu_get_dma_cookie(). Don't you need to do some cleanup for this latter? > if (!cookie) > return; > > @@ -1800,33 +1809,19 @@ static struct iommu_dma_msi_page *iommu_dma_get_msi_page(struct device *dev, > return NULL; > } > > -/** > - * iommu_dma_prepare_msi() - Map the MSI page in the IOMMU domain > - * @desc: MSI descriptor, will store the MSI page > - * @msi_addr: MSI target address to be mapped > - * > - * Return: 0 on success or negative error code if the mapping failed. > - */ > -int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr) > +static int iommu_dma_sw_msi(struct iommu_domain *domain, struct msi_desc *desc, > + phys_addr_t msi_addr) > { > struct device *dev = msi_desc_to_dev(desc); > - struct iommu_domain *domain = iommu_get_domain_for_dev(dev); > - struct iommu_dma_msi_page *msi_page; > - static DEFINE_MUTEX(msi_prepare_lock); /* see below */ > + const struct iommu_dma_msi_page *msi_page; > > - if (!domain || !domain->iova_cookie) { > + if (!domain->iova_cookie) { > msi_desc_set_iommu_msi_iova(desc, 0, 0); > return 0; > } > > - /* > - * In fact the whole prepare operation should already be serialised by > - * irq_domain_mutex further up the callchain, but that's pretty subtle > - * on its own, so consider this locking as failsafe documentation... > - */ > - mutex_lock(&msi_prepare_lock); > + iommu_group_mutex_assert(dev); > msi_page = iommu_dma_get_msi_page(dev, msi_addr, domain); > - mutex_unlock(&msi_prepare_lock); > if (!msi_page) > return -ENOMEM; > > diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c > index 599030e1e890..fbbbcdba8a4f 100644 > --- a/drivers/iommu/iommu.c > +++ b/drivers/iommu/iommu.c > @@ -3587,3 +3587,32 @@ int iommu_replace_group_handle(struct iommu_group *group, > return ret; > } > EXPORT_SYMBOL_NS_GPL(iommu_replace_group_handle, "IOMMUFD_INTERNAL"); > + > +#if IS_ENABLED(CONFIG_IRQ_MSI_IOMMU) > +/** > + * iommu_dma_prepare_msi() - Map the MSI page in the IOMMU domain > + * @desc: MSI descriptor, will store the MSI page > + * @msi_addr: MSI target address to be mapped > + * > + * The implementation of sw_msi() should take msi_addr and map it to > + * an IOVA in the domain and call msi_desc_set_iommu_msi_iova() with the > + * mapping information. > + * > + * Return: 0 on success or negative error code if the mapping failed. > + */ > +int iommu_dma_prepare_msi(struct msi_desc *desc, phys_addr_t msi_addr) > +{ > + struct device *dev = msi_desc_to_dev(desc); > + struct iommu_group *group = dev->iommu_group; > + int ret = 0; > + > + if (!group) > + return 0; > + > + mutex_lock(&group->mutex); > + if (group->domain && group->domain->sw_msi) > + ret = group->domain->sw_msi(group->domain, desc, msi_addr); > + mutex_unlock(&group->mutex); > + return ret; > +} > +#endif /* CONFIG_IRQ_MSI_IOMMU */ Thanks Eric