qiurui
/
Centos-kernel-stream-9
mirror of https://gitlab.com/redhat/centos-stream/src/kernel/centos-stream-9.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

vfio: Move the Intel no-snoop control off of IOMMU_CACHE 

Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=2124620
Conflicts: Context due to remaining iommu backing device support

commit 71cfafda9c9bd9812cdb62ddb94daf65a1af12c1
Author: Jason Gunthorpe <jgg@ziepe.ca>
Date:   Mon Apr 11 12:16:06 2022 -0300

    vfio: Move the Intel no-snoop control off of IOMMU_CACHE

    IOMMU_CACHE means "normal DMA to this iommu_domain's IOVA should be cache
    coherent" and is used by the DMA API. The definition allows for special
    non-coherent DMA to exist - ie processing of the no-snoop flag in PCIe
    TLPs - so long as this behavior is opt-in by the device driver.

    The flag is mainly used by the DMA API to synchronize the IOMMU setting
    with the expected cache behavior of the DMA master. eg based on
    dev_is_dma_coherent() in some case.

    For Intel IOMMU IOMMU_CACHE was redefined to mean 'force all DMA to be
    cache coherent' which has the practical effect of causing the IOMMU to
    ignore the no-snoop bit in a PCIe TLP.

    x86 platforms are always IOMMU_CACHE, so Intel should ignore this flag.

    Instead use the new domain op enforce_cache_coherency() which causes every
    IOPTE created in the domain to have the no-snoop blocking behavior.

    Reconfigure VFIO to always use IOMMU_CACHE and call
    enforce_cache_coherency() to operate the special Intel behavior.

    Remove the IOMMU_CACHE test from Intel IOMMU.

    Ultimately VFIO plumbs the result of enforce_cache_coherency() back into
    the x86 platform code through kvm_arch_register_noncoherent_dma() which
    controls if the WBINVD instruction is available in the guest.  No other
    archs implement kvm_arch_register_noncoherent_dma() nor are there any
    other known consumers of VFIO_DMA_CC_IOMMU that might be affected by the
    user visible result change on non-x86 archs.

    Reviewed-by: Kevin Tian <kevin.tian@intel.com>
    Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
    Acked-by: Alex Williamson <alex.williamson@redhat.com>
    Acked-by: Robin Murphy <robin.murphy@arm.com>
    Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
    Link: https://lore.kernel.org/r/2-v3-2cf356649677+a32-intel_no_snoop_jgg@nvidia.com
    Signed-off-by: Joerg Roedel <jroedel@suse.de>

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
This commit is contained in:
Alex Williamson 2022-08-02 14:49:59 -06:00
parent aa91a1020c
commit eaaab9be57
3 changed files with 21 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
drivers/iommu/intel/iommu.c
View File

@ -617,7 +617,6 @@ static unsigned long domain_super_pgsize_bitmap(struct dmar_domain *domain)
static void domain_update_iommu_cap(struct dmar_domain *domain)
{
domain_update_iommu_coherency(domain);
domain->iommu_snooping = domain_update_iommu_snooping(NULL);
domain->iommu_superpage = domain_update_iommu_superpage(domain, NULL);
/*
@ -4280,7 +4279,6 @@ static int md_domain_init(struct dmar_domain *domain, int guest_width)
domain->agaw = width_to_agaw(adjust_width);
domain->iommu_coherency = false;
domain->iommu_snooping = false;
domain->iommu_superpage = 0;
domain->max_addr = 0;
@ -4419,8 +4417,7 @@ static int intel_iommu_map(struct iommu_domain *domain,
prot |= DMA_PTE_READ;
if (iommu_prot & IOMMU_WRITE)
prot |= DMA_PTE_WRITE;
if (((iommu_prot & IOMMU_CACHE) && dmar_domain->iommu_snooping) ||
dmar_domain->force_snooping)
if (dmar_domain->force_snooping)
prot |= DMA_PTE_SNP;
max_addr = iova + size;
@ -4547,7 +4544,7 @@ static bool intel_iommu_enforce_cache_coherency(struct iommu_domain *domain)
{
struct dmar_domain *dmar_domain = to_dmar_domain(domain);
if (!dmar_domain->iommu_snooping)
if (!domain_update_iommu_snooping(NULL))
return false;
dmar_domain->force_snooping = true;
return true;

30
drivers/vfio/vfio_iommu_type1.c
View File

@ -85,8 +85,8 @@ struct vfio_domain {
struct iommu_domain *domain;
struct list_head next;
struct list_head group_list;
int prot; /* IOMMU_CACHE */
bool fgsp; /* Fine-grained super pages */
bool fgsp : 1; /* Fine-grained super pages */
bool enforce_cache_coherency : 1;
};
struct vfio_dma {
@ -1475,7 +1475,7 @@ static int vfio_iommu_map(struct vfio_iommu *iommu, dma_addr_t iova,
list_for_each_entry(d, &iommu->domain_list, next) {
ret = iommu_map(d->domain, iova, (phys_addr_t)pfn << PAGE_SHIFT,
npage << PAGE_SHIFT, prot | d->prot);
npage << PAGE_SHIFT, prot | IOMMU_CACHE);
if (ret)
goto unwind;
@ -1785,7 +1785,7 @@ static int vfio_iommu_replay(struct vfio_iommu *iommu,
}
ret = iommu_map(domain->domain, iova, phys,
size, dma->prot | domain->prot);
size, dma->prot | IOMMU_CACHE);
if (ret) {
if (!dma->iommu_mapped) {
vfio_unpin_pages_remote(dma, iova,
@ -1873,7 +1873,7 @@ static void vfio_test_domain_fgsp(struct vfio_domain *domain)
return;
ret = iommu_map(domain->domain, 0, page_to_phys(pages), PAGE_SIZE * 2,
IOMMU_READ | IOMMU_WRITE | domain->prot);
IOMMU_READ | IOMMU_WRITE | IOMMU_CACHE);
if (!ret) {
size_t unmapped = iommu_unmap(domain->domain, 0, PAGE_SIZE);
@ -2378,8 +2378,15 @@ rhel_mdev_iommu_device:
goto out_detach;
}
if (iommu_capable(bus, IOMMU_CAP_CACHE_COHERENCY))
domain->prot |= IOMMU_CACHE;
/*
* If the IOMMU can block non-coherent operations (ie PCIe TLPs with
* no-snoop set) then VFIO always turns this feature on because on Intel
* platforms it optimizes KVM to disable wbinvd emulation.
*/
if (domain->domain->ops->enforce_cache_coherency)
domain->enforce_cache_coherency =
domain->domain->ops->enforce_cache_coherency(
domain->domain);
/*
* Try to match an existing compatible domain. We don't want to
@ -2390,7 +2397,8 @@ rhel_mdev_iommu_device:
*/
list_for_each_entry(d, &iommu->domain_list, next) {
if (d->domain->ops == domain->domain->ops &&
d->prot == domain->prot) {
d->enforce_cache_coherency ==
domain->enforce_cache_coherency) {
vfio_iommu_detach_group(domain, group);
if (!vfio_iommu_attach_group(d, group)) {
list_add(&group->next, &d->group_list);
@ -2720,14 +2728,14 @@ static void vfio_iommu_type1_release(void *iommu_data)
kfree(iommu);
}
static int vfio_domains_have_iommu_cache(struct vfio_iommu *iommu)
static int vfio_domains_have_enforce_cache_coherency(struct vfio_iommu *iommu)
{
struct vfio_domain *domain;
int ret = 1;
mutex_lock(&iommu->lock);
list_for_each_entry(domain, &iommu->domain_list, next) {
if (!(domain->prot & IOMMU_CACHE)) {
if (!(domain->enforce_cache_coherency)) {
ret = 0;
break;
}
@ -2750,7 +2758,7 @@ static int vfio_iommu_type1_check_extension(struct vfio_iommu *iommu,
case VFIO_DMA_CC_IOMMU:
if (!iommu)
return 0;
return vfio_domains_have_iommu_cache(iommu);
return vfio_domains_have_enforce_cache_coherency(iommu);
default:
return 0;
}

1
include/linux/intel-iommu.h
View File

@ -539,7 +539,6 @@ struct dmar_domain {
u8 has_iotlb_device: 1;
u8 iommu_coherency: 1; /* indicate coherency of iommu access */
u8 iommu_snooping: 1; /* indicate snooping control feature */
u8 force_snooping : 1; /* Create IOPTEs with snoop control */
struct list_head devices; /* all devices' list */