by Alexey Kardashevskiy

[permalink] [raw]

Subject: Re: [RFC PATCH] PPC: KVM: vfio kvm device: support spapr tce

On 10/05/2013 11:52 AM, Alexey Kardashevskiy wrote:
> On 05.10.2013 2:05, Alex Williamson wrote:
>> On Fri, 2013-10-04 at 22:24 +1000, Alexey Kardashevskiy wrote:
>>> This is a very rough change set required for ppc64 to use this KVM device.
>>>
>>> vfio_rm.c is a piece of code which is going to be called from the realmode (MMU off),
>>> and I will put everything spapr-related under #ifdef CONFIG_SPAPR_TCE_IOMMU,
>>> it is just friday and I have to run :)
>>>
>>> This is an RFC but it works.
>>>
>>> Signed-off-by: Alexey Kardashevskiy <[email protected]>
>>> ---
>>> arch/powerpc/kvm/Kconfig | 1 +
>>> arch/powerpc/kvm/Makefile | 4 ++++
>>> include/linux/kvm_host.h | 8 ++++---
>>> include/linux/vfio.h | 3 +++
>>> include/uapi/linux/kvm.h | 1 +
>>> virt/kvm/vfio.c | 46 ++++++++++++++++++++++++++++++++++++++++
>>> virt/kvm/vfio_rm.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++
>>> 7 files changed, 114 insertions(+), 3 deletions(-)
>>> create mode 100644 virt/kvm/vfio_rm.c
>>>
>>> diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig
>>> index 61b3535..d1b7f64 100644
>>> --- a/arch/powerpc/kvm/Kconfig
>>> +++ b/arch/powerpc/kvm/Kconfig
>>> @@ -60,6 +60,7 @@ config KVM_BOOK3S_64
>>> select KVM_BOOK3S_64_HANDLER
>>> select KVM
>>> select SPAPR_TCE_IOMMU
>>> + select KVM_VFIO
>>> ---help---
>>> Support running unmodified book3s_64 and book3s_32 guest kernels
>>> in virtual machines on book3s_64 host processors.
>>> diff --git a/arch/powerpc/kvm/Makefile b/arch/powerpc/kvm/Makefile
>>> index 6646c95..fc2878b 100644
>>> --- a/arch/powerpc/kvm/Makefile
>>> +++ b/arch/powerpc/kvm/Makefile
>>> @@ -55,6 +55,8 @@ kvm-objs-$(CONFIG_KVM_E500MC) := $(kvm-e500mc-objs)
>>>
>>> kvm-book3s_64-objs-$(CONFIG_KVM_BOOK3S_64_PR) := \
>>> $(KVM)/coalesced_mmio.o \
>>> + $(KVM)/vfio.o \
>>> + $(KVM)/vfio_rm.o \
>>> fpu.o \
>>> book3s_paired_singles.o \
>>> book3s_pr.o \
>>> @@ -76,6 +78,7 @@ kvm-book3s_64-objs-$(CONFIG_KVM_BOOK3S_64_HV) := \
>>> kvm-book3s_64-builtin-xics-objs-$(CONFIG_KVM_XICS) := \
>>> book3s_hv_rm_xics.o
>>> kvm-book3s_64-builtin-objs-$(CONFIG_KVM_BOOK3S_64_HV) := \
>>> + $(KVM)/vfio_rm.o \
>>> book3s_hv_rmhandlers.o \
>>> book3s_hv_rm_mmu.o \
>>> book3s_64_vio_hv.o \
>>> @@ -89,6 +92,7 @@ kvm-book3s_64-objs-$(CONFIG_KVM_XICS) += \
>>>
>>> kvm-book3s_64-module-objs := \
>>> $(KVM)/kvm_main.o \
>>> + $(KVM)/vfio.o \
>>> $(KVM)/eventfd.o \
>>> powerpc.o \
>>> emulate.o \
>>> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
>>> index ad2b581..43c0290 100644
>>> --- a/include/linux/kvm_host.h
>>> +++ b/include/linux/kvm_host.h
>>> @@ -407,6 +407,8 @@ struct kvm {
>>> #endif
>>> long tlbs_dirty;
>>> struct list_head devices;
>>> +
>>> + struct kvm_vfio *vfio;
>>
>>
>> <cringe> can't this be on kvm->arch?
>
> It can, I just thought since it is valid for more than just one
> platform, it can go here.
>
>
>>> };
>>>
>>> #define kvm_err(fmt, ...) \
>>> @@ -677,15 +679,15 @@ void kvm_arch_register_noncoherent_dma(struct kvm *kvm);
>>> void kvm_arch_unregister_noncoherent_dma(struct kvm *kvm);
>>> bool kvm_arch_has_noncoherent_dma(struct kvm *kvm);
>>> #else
>>> -static inline void kvm_arch_register_noncoherent_dma(void)
>>> +static inline void kvm_arch_register_noncoherent_dma(struct kvm *kvm)
>>> {
>>> }
>>>
>>> -static inline void kvm_arch_unregister_noncoherent_dma(void)
>>> +static inline void kvm_arch_unregister_noncoherent_dma(struct kvm *kvm)
>>> {
>>> }
>>>
>>> -static inline bool kvm_arch_has_noncoherent_dma(void)
>>> +static inline bool kvm_arch_has_noncoherent_dma(struct kvm *kvm)
>>> {
>>> return false;
>>> }
>>
>> Will fix in my series.
>>
>>> diff --git a/include/linux/vfio.h b/include/linux/vfio.h
>>> index 24579a0..681e19b 100644
>>> --- a/include/linux/vfio.h
>>> +++ b/include/linux/vfio.h
>>> @@ -97,4 +97,7 @@ extern struct vfio_group *vfio_group_get_external_user(struct file *filep);
>>> extern void vfio_group_put_external_user(struct vfio_group *group);
>>> extern int vfio_external_user_iommu_id(struct vfio_group *group);
>>>
>>> +extern struct iommu_group *vfio_find_group_by_liobn(struct kvm *kvm,
>>> + unsigned long liobn);
>>> +
>>
>> Wrong header file.

btw there are two - uapi/linux/vfio.h and linux/vfio.h. The external user
API is in linux/vfio.h but my change should go to uapi/linux/vfio.h, is
that correct? Or we need a third header? Just asking, no kidding, no arguing :)

>>
>>> #endif /* VFIO_H */
>>> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
>>> index 7c1a349..a74ad16 100644
>>> --- a/include/uapi/linux/kvm.h
>>> +++ b/include/uapi/linux/kvm.h
>>> @@ -847,6 +847,7 @@ struct kvm_device_attr {
>>> #define KVM_DEV_VFIO_GROUP 1
>>> #define KVM_DEV_VFIO_GROUP_ADD 1
>>> #define KVM_DEV_VFIO_GROUP_DEL 2
>>> +#define KVM_DEV_VFIO_SPAPR_TCE_LIOBN 2
>>>
>>> /*
>>> * ioctls for VM fds
>>> diff --git a/virt/kvm/vfio.c b/virt/kvm/vfio.c
>>> index 2e336a7..39dea9f 100644
>>> --- a/virt/kvm/vfio.c
>>> +++ b/virt/kvm/vfio.c
>>> @@ -22,6 +22,7 @@
>>> struct kvm_vfio_group {
>>> struct list_head node;
>>> struct vfio_group *vfio_group;
>>> + uint64_t liobn; /* sPAPR */
>>
>> Perhaps an arch pointer or at least a union.
>>
>>> };
>>>
>>> struct kvm_vfio {
>>> @@ -188,12 +189,52 @@ static int kvm_vfio_set_group(struct kvm_device *dev, long attr, u64 arg)
>>> return -ENXIO;
>>> }
>>>
>>> +static int kvm_vfio_set_spapr_tce_liobn(struct kvm_device *dev,
>>> + long attr, u64 arg)
>>> +{
>>> + struct kvm_vfio *kv = dev->private;
>>> + struct vfio_group *vfio_group;
>>> + struct kvm_vfio_group *kvg;
>>> + void __user *argp = (void __user *)arg;
>>> + struct fd f;
>>> + int32_t fd;
>>> + uint64_t liobn = attr;
>>> +
>>> + if (get_user(fd, (int32_t __user *)argp))
>>> + return -EFAULT;
>>> +
>>> + f = fdget(fd);
>>> + if (!f.file)
>>> + return -EBADF;
>>> +
>>> + vfio_group = kvm_vfio_group_get_external_user(f.file);
>>> + fdput(f);
>>> +
>>> + list_for_each_entry(kvg, &kv->group_list, node) {
>>> + if (kvg->vfio_group == vfio_group) {
>>> + WARN_ON(kvg->liobn);
>>
>> Users shouldn't be able to trigger WARN_ON so easily, return -EBUSY,
>> allow it to be unset and re-set, or just allow the overwrite.
>>
>>> + kvg->liobn = liobn;
>>> + kvm_vfio_group_put_external_user(vfio_group);
>>> + return 0;
>>> + }
>>> + }
>>> +
>>> + kvm_vfio_group_put_external_user(vfio_group);
>>> +
>>> + return -ENXIO;
>>> +}
>>> +
>>> static int kvm_vfio_set_attr(struct kvm_device *dev,
>>> struct kvm_device_attr *attr)
>>> {
>>> switch (attr->group) {
>>> case KVM_DEV_VFIO_GROUP:
>>> return kvm_vfio_set_group(dev, attr->attr, attr->addr);
>>> +#ifdef CONFIG_SPAPR_TCE_IOMMU
>>> + case KVM_DEV_VFIO_SPAPR_TCE_LIOBN:
>>> + return kvm_vfio_set_spapr_tce_liobn(dev, attr->attr,
>>> + attr->addr);
>>> +#endif
>>> }
>>>
>>> return -ENXIO;
>>> @@ -211,6 +252,10 @@ static int kvm_vfio_has_attr(struct kvm_device *dev,
>>> }
>>>
>>> break;
>>> +#ifdef CONFIG_SPAPR_TCE_IOMMU
>>> + case KVM_DEV_VFIO_SPAPR_TCE_LIOBN:
>>> + return 0;
>>> +#endif
>>> }
>>>
>>> return -ENXIO;
>>> @@ -250,6 +295,7 @@ static int kvm_vfio_create(struct kvm_device *dev, u32 type)
>>> mutex_init(&kv->lock);
>>>
>>> dev->private = kv;
>>> + dev->kvm->vfio = kv;
>>>
>>> return 0;
>>> }
>>> diff --git a/virt/kvm/vfio_rm.c b/virt/kvm/vfio_rm.c
>>> new file mode 100644
>>> index 0000000..ee9fd96
>>> --- /dev/null
>>> +++ b/virt/kvm/vfio_rm.c
>>> @@ -0,0 +1,54 @@
>>> +#include <linux/errno.h>
>>> +#include <linux/file.h>
>>> +#include <linux/kvm_host.h>
>>> +#include <linux/list.h>
>>> +#include <linux/module.h>
>>> +#include <linux/mutex.h>
>>> +#include <linux/slab.h>
>>> +#include <linux/uaccess.h>
>>> +#include <linux/vfio.h>
>>> +
>>> +struct kvm_vfio_group {
>>> + struct list_head node;
>>> + struct vfio_group *vfio_group;
>>> + uint64_t liobn; /* sPAPR */
>>> +};
>>> +
>>> +struct kvm_vfio {
>>> + struct list_head group_list;
>>> + struct mutex lock;
>>> + bool noncoherent;
>>> +};
>>> +
>>> +struct vfio_group {
>>> + struct kref kref;
>>> + int minor;
>>> + atomic_t container_users;
>>> + struct iommu_group *iommu_group;
>>> + struct vfio_container *container;
>>> + struct list_head device_list;
>>> + struct mutex device_lock;
>>> + struct device *dev;
>>> + struct notifier_block nb;
>>> + struct list_head vfio_next;
>>> + struct list_head container_next;
>>> + atomic_t opened;
>>> +};
>>> +
>>> +struct iommu_group *vfio_find_group_by_liobn(struct kvm *kvm, unsigned long liobn)
>>> +{
>>> + struct kvm_vfio_group *kvg;
>>> +
>>> + if (!kvm->vfio)
>>> + return NULL;
>>> +
>>> + list_for_each_entry(kvg, &kvm->vfio->group_list, node) {
>>> + if (kvg->liobn == liobn)
>>> + return kvg->vfio_group->iommu_group;
>>> + }
>>> +
>>> + return NULL;
>>> +}
>>> +EXPORT_SYMBOL_GPL(vfio_find_group_by_liobn);
>>> +
>>> +
>>
>> You're kidding, right? These are intentionally private data structures
>> that are blatantly copied so that you can extract what you want. NACK.
>> The iommu_group is available off struct device, do you even need vfio or
>> this kvm-vfio device to get from liobn to iommu_group? Thanks,
>
>
> This is an RFC. I am not saying this is what can go to upstream or
> anything. I am not kidding (why everyone assumes that?), I am showing
> what API I would like to have in the VFIO KVM device. I need the way to
> get iommu_table (which is in a private data of iommu_group) by LIOBN and
> the VFIO KVM device is the _only_ entity which will know about this
> connection (LIOBN is made up by the qemu and told to the guest) and it
> cannot go to the kvm.ko - and the patch like this is the best way to
> show it as my english obviously sucks.

Oh. I was confused by:
drivers/vfio/vfio.c|67| struct vfio_group {
drivers/vfio/vfio_iommu_type1.c|73| struct vfio_group {

which are two completely different types (confusing).

So. I either need an additional file to compile to the kernel for mmu-off
case (such as vfio_rm.c) and share vfio_group struct via some internal
header or compile vfio.c into the kernel image always, in this case I'll
need to export kvm_vfio_ops symbol. What would you suggest?

--
Alexey