[v2,1/4] IOMMU/x86: switch to alternatives-call patching in further instances

Commit Message

Jan Beulich Jan. 27, 2022, 2:47 p.m. UTC

This is, once again, to limit the number of indirect calls as much as
possible. The only hook invocation which isn't sensible to convert is
setup(). And of course Arm-only use sites are left alone as well.

Note regarding the introduction / use of local variables in pci.c:
struct pci_dev's involved fields are const. This const propagates, via
typeof(), to the local helper variables in the altcall macros. These
helper variables are, however, used as outputs (and hence can't be
const). In iommu_get_device_group() make use of the new local variables
to also simplify some adjacent code.

Signed-off-by: Jan Beulich <[e-mail]>

Comments

Paul Durrant Jan. 28, 2022, 9:28 a.m. UTC | #1

On 27/01/2022 14:47, Jan Beulich wrote:
> This is, once again, to limit the number of indirect calls as much as
> possible. The only hook invocation which isn't sensible to convert is
> setup(). And of course Arm-only use sites are left alone as well.
> 
> Note regarding the introduction / use of local variables in pci.c:
> struct pci_dev's involved fields are const. This const propagates, via
> typeof(), to the local helper variables in the altcall macros. These
> helper variables are, however, used as outputs (and hence can't be
> const). In iommu_get_device_group() make use of the new local variables
> to also simplify some adjacent code.
> 
> Signed-off-by: Jan Beulich <[e-mail]>
> 
> --- a/xen/drivers/passthrough/iommu.c
> +++ b/xen/drivers/passthrough/iommu.c
> @@ -198,7 +198,7 @@ int iommu_domain_init(struct domain *d,
>           return ret;
>   
>       hd->platform_ops = iommu_get_ops();
> -    ret = hd->platform_ops->init(d);
> +    ret = iommu_call(hd->platform_ops, init, d);
>       if ( ret || is_system_domain(d) )
>           return ret;
>   
> @@ -233,7 +233,7 @@ void __hwdom_init iommu_hwdom_init(struc
>   
>       register_keyhandler('o', &iommu_dump_page_tables, "dump iommu page tables", 0);
>   
> -    hd->platform_ops->hwdom_init(d);
> +    iommu_vcall(hd->platform_ops, hwdom_init, d);
>   }
>   
>   static void iommu_teardown(struct domain *d)
> @@ -576,7 +576,7 @@ int iommu_get_reserved_device_memory(iom
>       if ( !ops->get_reserved_device_memory )
>           return 0;
>   
> -    return ops->get_reserved_device_memory(func, ctxt);
> +    return iommu_call(ops, get_reserved_device_memory, func, ctxt);
>   }
>   
>   bool_t iommu_has_feature(struct domain *d, enum iommu_feature feature)
> @@ -603,7 +603,7 @@ static void iommu_dump_page_tables(unsig
>               continue;
>           }
>   
> -        dom_iommu(d)->platform_ops->dump_page_tables(d);
> +        iommu_vcall(dom_iommu(d)->platform_ops, dump_page_tables, d);
>       }
>   
>       rcu_read_unlock(&domlist_read_lock);
> --- a/xen/drivers/passthrough/pci.c
> +++ b/xen/drivers/passthrough/pci.c
> @@ -861,15 +861,15 @@ static int deassign_device(struct domain
>           devfn += pdev->phantom_stride;
>           if ( PCI_SLOT(devfn) != PCI_SLOT(pdev->devfn) )
>               break;
> -        ret = hd->platform_ops->reassign_device(d, target, devfn,
> -                                                pci_to_dev(pdev));
> +        ret = iommu_call(hd->platform_ops, reassign_device, d, target, devfn,
> +                         pci_to_dev(pdev));
>           if ( ret )
>               goto out;
>       }
>   
>       devfn = pdev->devfn;
> -    ret = hd->platform_ops->reassign_device(d, target, devfn,
> -                                            pci_to_dev(pdev));
> +    ret = iommu_call(hd->platform_ops, reassign_device, d, target, devfn,
> +                     pci_to_dev(pdev));
>       if ( ret )
>           goto out;
>   
> @@ -1300,7 +1300,7 @@ static int iommu_add_device(struct pci_d
>   {
>       const struct domain_iommu *hd;
>       int rc;
> -    u8 devfn;
> +    unsigned int devfn = pdev->devfn;
>   
>       if ( !pdev->domain )
>           return -EINVAL;
> @@ -1311,16 +1311,16 @@ static int iommu_add_device(struct pci_d
>       if ( !is_iommu_enabled(pdev->domain) )
>           return 0;
>   
> -    rc = hd->platform_ops->add_device(pdev->devfn, pci_to_dev(pdev));
> +    rc = iommu_call(hd->platform_ops, add_device, devfn, pci_to_dev(pdev));
>       if ( rc || !pdev->phantom_stride )
>           return rc;
>   
> -    for ( devfn = pdev->devfn ; ; )
> +    for ( ; ; )
>       {
>           devfn += pdev->phantom_stride;
>           if ( PCI_SLOT(devfn) != PCI_SLOT(pdev->devfn) )
>               return 0;
> -        rc = hd->platform_ops->add_device(devfn, pci_to_dev(pdev));
> +        rc = iommu_call(hd->platform_ops, add_device, devfn, pci_to_dev(pdev));
>           if ( rc )
>               printk(XENLOG_WARNING "IOMMU: add %pp failed (%d)\n",
>                      &pdev->sbdf, rc);
> @@ -1341,7 +1341,7 @@ static int iommu_enable_device(struct pc
>            !hd->platform_ops->enable_device )
>           return 0;
>   
> -    return hd->platform_ops->enable_device(pci_to_dev(pdev));
> +    return iommu_call(hd->platform_ops, enable_device, pci_to_dev(pdev));
>   }
>   
>   static int iommu_remove_device(struct pci_dev *pdev)
> @@ -1363,7 +1363,8 @@ static int iommu_remove_device(struct pc
>           devfn += pdev->phantom_stride;
>           if ( PCI_SLOT(devfn) != PCI_SLOT(pdev->devfn) )
>               break;
> -        rc = hd->platform_ops->remove_device(devfn, pci_to_dev(pdev));
> +        rc = iommu_call(hd->platform_ops, remove_device, devfn,
> +                        pci_to_dev(pdev));
>           if ( !rc )
>               continue;
>   
> @@ -1371,7 +1372,9 @@ static int iommu_remove_device(struct pc
>           return rc;
>       }
>   
> -    return hd->platform_ops->remove_device(pdev->devfn, pci_to_dev(pdev));
> +    devfn = pdev->devfn;
> +
> +    return iommu_call(hd->platform_ops, remove_device, devfn, pci_to_dev(pdev));
>   }
>   
>   static int device_assigned(u16 seg, u8 bus, u8 devfn)
> @@ -1421,7 +1424,8 @@ static int assign_device(struct domain *
>   
>       pdev->fault.count = 0;
>   
> -    if ( (rc = hd->platform_ops->assign_device(d, devfn, pci_to_dev(pdev), flag)) )
> +    if ( (rc = iommu_call(hd->platform_ops, assign_device, d, devfn,
> +                          pci_to_dev(pdev), flag)) )
>           goto done;
>   
>       for ( ; pdev->phantom_stride; rc = 0 )
> @@ -1429,7 +1433,8 @@ static int assign_device(struct domain *
>           devfn += pdev->phantom_stride;
>           if ( PCI_SLOT(devfn) != PCI_SLOT(pdev->devfn) )
>               break;
> -        rc = hd->platform_ops->assign_device(d, devfn, pci_to_dev(pdev), flag);
> +        rc = iommu_call(hd->platform_ops, assign_device, d, devfn,
> +                        pci_to_dev(pdev), flag);
>       }
>   
>    done:
> @@ -1457,24 +1462,24 @@ static int iommu_get_device_group(
>       if ( !is_iommu_enabled(d) || !ops->get_device_group_id )
>           return 0;
>   
> -    group_id = ops->get_device_group_id(seg, bus, devfn);
> +    group_id = iommu_call(ops, get_device_group_id, seg, bus, devfn);
>   
>       pcidevs_lock();
>       for_each_pdev( d, pdev )
>       {
> -        if ( (pdev->seg != seg) ||
> -             ((pdev->bus == bus) && (pdev->devfn == devfn)) )
> +        unsigned int b = pdev->bus;
> +        unsigned int df = pdev->devfn;
> +
> +        if ( (pdev->seg != seg) || ((b == bus) && (df == devfn)) )
>               continue;
>   
> -        if ( xsm_get_device_group(XSM_HOOK, (seg << 16) | (pdev->bus << 8) | pdev->devfn) )
> +        if ( xsm_get_device_group(XSM_HOOK, (seg << 16) | (b << 8) | df) )
>               continue;
>   
> -        sdev_id = ops->get_device_group_id(seg, pdev->bus, pdev->devfn);
> +        sdev_id = iommu_call(ops, get_device_group_id, seg, b, df);
>           if ( (sdev_id == group_id) && (i < max_sdevs) )
>           {
> -            bdf = 0;
> -            bdf |= (pdev->bus & 0xff) << 16;
> -            bdf |= (pdev->devfn & 0xff) << 8;
> +            bdf = (b << 16) | (df << 8);

Don't we have a macro for this now? Probably best to start using it 
whilst modifying the code.

Anyway...

Reviewed-by: Paul Durrant <[e-mail]>

>   
>               if ( unlikely(copy_to_guest_offset(buf, i, &bdf, 1)) )
>               {
> --- a/xen/drivers/passthrough/x86/iommu.c
> +++ b/xen/drivers/passthrough/x86/iommu.c
> @@ -145,7 +145,7 @@ unsigned int iommu_read_apic_from_ire(un
>   int __init iommu_setup_hpet_msi(struct msi_desc *msi)
>   {
>       const struct iommu_ops *ops = iommu_get_ops();
> -    return ops->setup_hpet_msi ? ops->setup_hpet_msi(msi) : -ENODEV;
> +    return ops->setup_hpet_msi ? iommu_call(ops, setup_hpet_msi, msi) : -ENODEV;
>   }
>   
>   void __hwdom_init arch_iommu_check_autotranslated_hwdom(struct domain *d)
> @@ -406,7 +406,7 @@ int iommu_free_pgtables(struct domain *d
>        * Pages will be moved to the free list below. So we want to
>        * clear the root page-table to avoid any potential use after-free.
>        */
> -    hd->platform_ops->clear_root_pgtable(d);
> +    iommu_vcall(hd->platform_ops, clear_root_pgtable, d);
>   
>       while ( (pg = page_list_remove_head(&hd->arch.pgtables.list)) )
>       {
>

Jan Beulich Jan. 28, 2022, 10:36 a.m. UTC | #2

On 28.01.2022 10:28, Durrant, Paul wrote:
> On 27/01/2022 14:47, Jan Beulich wrote:
>> @@ -1457,24 +1462,24 @@ static int iommu_get_device_group(
>>       if ( !is_iommu_enabled(d) || !ops->get_device_group_id )
>>           return 0;
>>   
>> -    group_id = ops->get_device_group_id(seg, bus, devfn);
>> +    group_id = iommu_call(ops, get_device_group_id, seg, bus, devfn);
>>   
>>       pcidevs_lock();
>>       for_each_pdev( d, pdev )
>>       {
>> -        if ( (pdev->seg != seg) ||
>> -             ((pdev->bus == bus) && (pdev->devfn == devfn)) )
>> +        unsigned int b = pdev->bus;
>> +        unsigned int df = pdev->devfn;
>> +
>> +        if ( (pdev->seg != seg) || ((b == bus) && (df == devfn)) )
>>               continue;
>>   
>> -        if ( xsm_get_device_group(XSM_HOOK, (seg << 16) | (pdev->bus << 8) | pdev->devfn) )
>> +        if ( xsm_get_device_group(XSM_HOOK, (seg << 16) | (b << 8) | df) )
>>               continue;
>>   
>> -        sdev_id = ops->get_device_group_id(seg, pdev->bus, pdev->devfn);
>> +        sdev_id = iommu_call(ops, get_device_group_id, seg, b, df);
>>           if ( (sdev_id == group_id) && (i < max_sdevs) )
>>           {
>> -            bdf = 0;
>> -            bdf |= (pdev->bus & 0xff) << 16;
>> -            bdf |= (pdev->devfn & 0xff) << 8;
>> +            bdf = (b << 16) | (df << 8);
> 
> Don't we have a macro for this now? Probably best to start using it 
> whilst modifying the code.

We don't. And it would feel somewhat misleading to use PCI_BDF2(b, df) << 8
here. The situation is even worse imo: Besides there not being a macro, I
also cannot seem to find any documentation on this non-standard layout (BDF
shifted left by 8). Yet then again I also can't spot any caller of
xc_get_device_group() ...

> Reviewed-by: Paul Durrant <[e-mail]>

Thanks.

Jan

Rahul Singh Jan. 28, 2022, 10:40 a.m. UTC | #3

Hi Jan,

> On 27 Jan 2022, at 2:47 pm, Jan Beulich <[e-mail]> wrote:
> 
> This is, once again, to limit the number of indirect calls as much as
> possible. The only hook invocation which isn't sensible to convert is
> setup(). And of course Arm-only use sites are left alone as well.
> 
> Note regarding the introduction / use of local variables in pci.c:
> struct pci_dev's involved fields are const. This const propagates, via
> typeof(), to the local helper variables in the altcall macros. These
> helper variables are, however, used as outputs (and hence can't be
> const). In iommu_get_device_group() make use of the new local variables
> to also simplify some adjacent code.
> 
> Signed-off-by: Jan Beulich <[e-mail]>

Reviewed-by: Rahul Singh <[e-mail]>
Tested-by: Rahul Singh <[e-mail]>

Regards,
Rahul
> 
> --- a/xen/drivers/passthrough/iommu.c
> +++ b/xen/drivers/passthrough/iommu.c
> @@ -198,7 +198,7 @@ int iommu_domain_init(struct domain *d,
>         return ret;
> 
>     hd->platform_ops = iommu_get_ops();
> -    ret = hd->platform_ops->init(d);
> +    ret = iommu_call(hd->platform_ops, init, d);
>     if ( ret || is_system_domain(d) )
>         return ret;
> 
> @@ -233,7 +233,7 @@ void __hwdom_init iommu_hwdom_init(struc
> 
>     register_keyhandler('o', &iommu_dump_page_tables, "dump iommu page tables", 0);
> 
> -    hd->platform_ops->hwdom_init(d);
> +    iommu_vcall(hd->platform_ops, hwdom_init, d);
> }
> 
> static void iommu_teardown(struct domain *d)
> @@ -576,7 +576,7 @@ int iommu_get_reserved_device_memory(iom
>     if ( !ops->get_reserved_device_memory )
>         return 0;
> 
> -    return ops->get_reserved_device_memory(func, ctxt);
> +    return iommu_call(ops, get_reserved_device_memory, func, ctxt);
> }
> 
> bool_t iommu_has_feature(struct domain *d, enum iommu_feature feature)
> @@ -603,7 +603,7 @@ static void iommu_dump_page_tables(unsig
>             continue;
>         }
> 
> -        dom_iommu(d)->platform_ops->dump_page_tables(d);
> +        iommu_vcall(dom_iommu(d)->platform_ops, dump_page_tables, d);
>     }
> 
>     rcu_read_unlock(&domlist_read_lock);
> --- a/xen/drivers/passthrough/pci.c
> +++ b/xen/drivers/passthrough/pci.c
> @@ -861,15 +861,15 @@ static int deassign_device(struct domain
>         devfn += pdev->phantom_stride;
>         if ( PCI_SLOT(devfn) != PCI_SLOT(pdev->devfn) )
>             break;
> -        ret = hd->platform_ops->reassign_device(d, target, devfn,
> -                                                pci_to_dev(pdev));
> +        ret = iommu_call(hd->platform_ops, reassign_device, d, target, devfn,
> +                         pci_to_dev(pdev));
>         if ( ret )
>             goto out;
>     }
> 
>     devfn = pdev->devfn;
> -    ret = hd->platform_ops->reassign_device(d, target, devfn,
> -                                            pci_to_dev(pdev));
> +    ret = iommu_call(hd->platform_ops, reassign_device, d, target, devfn,
> +                     pci_to_dev(pdev));
>     if ( ret )
>         goto out;
> 
> @@ -1300,7 +1300,7 @@ static int iommu_add_device(struct pci_d
> {
>     const struct domain_iommu *hd;
>     int rc;
> -    u8 devfn;
> +    unsigned int devfn = pdev->devfn;
> 
>     if ( !pdev->domain )
>         return -EINVAL;
> @@ -1311,16 +1311,16 @@ static int iommu_add_device(struct pci_d
>     if ( !is_iommu_enabled(pdev->domain) )
>         return 0;
> 
> -    rc = hd->platform_ops->add_device(pdev->devfn, pci_to_dev(pdev));
> +    rc = iommu_call(hd->platform_ops, add_device, devfn, pci_to_dev(pdev));
>     if ( rc || !pdev->phantom_stride )
>         return rc;
> 
> -    for ( devfn = pdev->devfn ; ; )
> +    for ( ; ; )
>     {
>         devfn += pdev->phantom_stride;
>         if ( PCI_SLOT(devfn) != PCI_SLOT(pdev->devfn) )
>             return 0;
> -        rc = hd->platform_ops->add_device(devfn, pci_to_dev(pdev));
> +        rc = iommu_call(hd->platform_ops, add_device, devfn, pci_to_dev(pdev));
>         if ( rc )
>             printk(XENLOG_WARNING "IOMMU: add %pp failed (%d)\n",
>                    &pdev->sbdf, rc);
> @@ -1341,7 +1341,7 @@ static int iommu_enable_device(struct pc
>          !hd->platform_ops->enable_device )
>         return 0;
> 
> -    return hd->platform_ops->enable_device(pci_to_dev(pdev));
> +    return iommu_call(hd->platform_ops, enable_device, pci_to_dev(pdev));
> }
> 
> static int iommu_remove_device(struct pci_dev *pdev)
> @@ -1363,7 +1363,8 @@ static int iommu_remove_device(struct pc
>         devfn += pdev->phantom_stride;
>         if ( PCI_SLOT(devfn) != PCI_SLOT(pdev->devfn) )
>             break;
> -        rc = hd->platform_ops->remove_device(devfn, pci_to_dev(pdev));
> +        rc = iommu_call(hd->platform_ops, remove_device, devfn,
> +                        pci_to_dev(pdev));
>         if ( !rc )
>             continue;
> 
> @@ -1371,7 +1372,9 @@ static int iommu_remove_device(struct pc
>         return rc;
>     }
> 
> -    return hd->platform_ops->remove_device(pdev->devfn, pci_to_dev(pdev));
> +    devfn = pdev->devfn;
> +
> +    return iommu_call(hd->platform_ops, remove_device, devfn, pci_to_dev(pdev));
> }
> 
> static int device_assigned(u16 seg, u8 bus, u8 devfn)
> @@ -1421,7 +1424,8 @@ static int assign_device(struct domain *
> 
>     pdev->fault.count = 0;
> 
> -    if ( (rc = hd->platform_ops->assign_device(d, devfn, pci_to_dev(pdev), flag)) )
> +    if ( (rc = iommu_call(hd->platform_ops, assign_device, d, devfn,
> +                          pci_to_dev(pdev), flag)) )
>         goto done;
> 
>     for ( ; pdev->phantom_stride; rc = 0 )
> @@ -1429,7 +1433,8 @@ static int assign_device(struct domain *
>         devfn += pdev->phantom_stride;
>         if ( PCI_SLOT(devfn) != PCI_SLOT(pdev->devfn) )
>             break;
> -        rc = hd->platform_ops->assign_device(d, devfn, pci_to_dev(pdev), flag);
> +        rc = iommu_call(hd->platform_ops, assign_device, d, devfn,
> +                        pci_to_dev(pdev), flag);
>     }
> 
>  done:
> @@ -1457,24 +1462,24 @@ static int iommu_get_device_group(
>     if ( !is_iommu_enabled(d) || !ops->get_device_group_id )
>         return 0;
> 
> -    group_id = ops->get_device_group_id(seg, bus, devfn);
> +    group_id = iommu_call(ops, get_device_group_id, seg, bus, devfn);
> 
>     pcidevs_lock();
>     for_each_pdev( d, pdev )
>     {
> -        if ( (pdev->seg != seg) ||
> -             ((pdev->bus == bus) && (pdev->devfn == devfn)) )
> +        unsigned int b = pdev->bus;
> +        unsigned int df = pdev->devfn;
> +
> +        if ( (pdev->seg != seg) || ((b == bus) && (df == devfn)) )
>             continue;
> 
> -        if ( xsm_get_device_group(XSM_HOOK, (seg << 16) | (pdev->bus << 8) | pdev->devfn) )
> +        if ( xsm_get_device_group(XSM_HOOK, (seg << 16) | (b << 8) | df) )
>             continue;
> 
> -        sdev_id = ops->get_device_group_id(seg, pdev->bus, pdev->devfn);
> +        sdev_id = iommu_call(ops, get_device_group_id, seg, b, df);
>         if ( (sdev_id == group_id) && (i < max_sdevs) )
>         {
> -            bdf = 0;
> -            bdf |= (pdev->bus & 0xff) << 16;
> -            bdf |= (pdev->devfn & 0xff) << 8;
> +            bdf = (b << 16) | (df << 8);
> 
>             if ( unlikely(copy_to_guest_offset(buf, i, &bdf, 1)) )
>             {
> --- a/xen/drivers/passthrough/x86/iommu.c
> +++ b/xen/drivers/passthrough/x86/iommu.c
> @@ -145,7 +145,7 @@ unsigned int iommu_read_apic_from_ire(un
> int __init iommu_setup_hpet_msi(struct msi_desc *msi)
> {
>     const struct iommu_ops *ops = iommu_get_ops();
> -    return ops->setup_hpet_msi ? ops->setup_hpet_msi(msi) : -ENODEV;
> +    return ops->setup_hpet_msi ? iommu_call(ops, setup_hpet_msi, msi) : -ENODEV;
> }
> 
> void __hwdom_init arch_iommu_check_autotranslated_hwdom(struct domain *d)
> @@ -406,7 +406,7 @@ int iommu_free_pgtables(struct domain *d
>      * Pages will be moved to the free list below. So we want to
>      * clear the root page-table to avoid any potential use after-free.
>      */
> -    hd->platform_ops->clear_root_pgtable(d);
> +    iommu_vcall(hd->platform_ops, clear_root_pgtable, d);
> 
>     while ( (pg = page_list_remove_head(&hd->arch.pgtables.list)) )
>     {
> 
>

Andrew Cooper Jan. 28, 2022, 10:54 a.m. UTC | #4

On 28/01/2022 10:36, Jan Beulich wrote:
> On 28.01.2022 10:28, Durrant, Paul wrote:
>> On 27/01/2022 14:47, Jan Beulich wrote:
>>> @@ -1457,24 +1462,24 @@ static int iommu_get_device_group(
>>>       if ( !is_iommu_enabled(d) || !ops->get_device_group_id )
>>>           return 0;
>>>   
>>> -    group_id = ops->get_device_group_id(seg, bus, devfn);
>>> +    group_id = iommu_call(ops, get_device_group_id, seg, bus, devfn);
>>>   
>>>       pcidevs_lock();
>>>       for_each_pdev( d, pdev )
>>>       {
>>> -        if ( (pdev->seg != seg) ||
>>> -             ((pdev->bus == bus) && (pdev->devfn == devfn)) )
>>> +        unsigned int b = pdev->bus;
>>> +        unsigned int df = pdev->devfn;
>>> +
>>> +        if ( (pdev->seg != seg) || ((b == bus) && (df == devfn)) )
>>>               continue;
>>>   
>>> -        if ( xsm_get_device_group(XSM_HOOK, (seg << 16) | (pdev->bus << 8) | pdev->devfn) )
>>> +        if ( xsm_get_device_group(XSM_HOOK, (seg << 16) | (b << 8) | df) )
>>>               continue;
>>>   
>>> -        sdev_id = ops->get_device_group_id(seg, pdev->bus, pdev->devfn);
>>> +        sdev_id = iommu_call(ops, get_device_group_id, seg, b, df);
>>>           if ( (sdev_id == group_id) && (i < max_sdevs) )
>>>           {
>>> -            bdf = 0;
>>> -            bdf |= (pdev->bus & 0xff) << 16;
>>> -            bdf |= (pdev->devfn & 0xff) << 8;
>>> +            bdf = (b << 16) | (df << 8);
>> Don't we have a macro for this now? Probably best to start using it 
>> whilst modifying the code.
> We don't. And it would feel somewhat misleading to use PCI_BDF2(b, df) << 8
> here. The situation is even worse imo: Besides there not being a macro, I
> also cannot seem to find any documentation on this non-standard layout (BDF
> shifted left by 8). Yet then again I also can't spot any caller of
> xc_get_device_group() ...

I'm sure I already did the archaeology.

device groups were broken by a hypercall bounce buffering change 2 years
before the only caller was dropped with Xend.

This mess of a hypercall has demonstrably not been used in a decade.  I
firmly suggest dropping it, rather than wasting effort trying to unbreak
an interface which needs deleting anyway as the first step to doing
IOMMU groups.

~Andrew

Patch

--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -198,7 +198,7 @@  int iommu_domain_init(struct domain *d,
         return ret;
 
     hd->platform_ops = iommu_get_ops();
-    ret = hd->platform_ops->init(d);
+    ret = iommu_call(hd->platform_ops, init, d);
     if ( ret || is_system_domain(d) )
         return ret;
 
@@ -233,7 +233,7 @@  void __hwdom_init iommu_hwdom_init(struc
 
     register_keyhandler('o', &iommu_dump_page_tables, "dump iommu page tables", 0);
 
-    hd->platform_ops->hwdom_init(d);
+    iommu_vcall(hd->platform_ops, hwdom_init, d);
 }
 
 static void iommu_teardown(struct domain *d)
@@ -576,7 +576,7 @@  int iommu_get_reserved_device_memory(iom
     if ( !ops->get_reserved_device_memory )
         return 0;
 
-    return ops->get_reserved_device_memory(func, ctxt);
+    return iommu_call(ops, get_reserved_device_memory, func, ctxt);
 }
 
 bool_t iommu_has_feature(struct domain *d, enum iommu_feature feature)
@@ -603,7 +603,7 @@  static void iommu_dump_page_tables(unsig
             continue;
         }
 
-        dom_iommu(d)->platform_ops->dump_page_tables(d);
+        iommu_vcall(dom_iommu(d)->platform_ops, dump_page_tables, d);
     }
 
     rcu_read_unlock(&domlist_read_lock);
--- a/xen/drivers/passthrough/pci.c
+++ b/xen/drivers/passthrough/pci.c
@@ -861,15 +861,15 @@  static int deassign_device(struct domain
         devfn += pdev->phantom_stride;
         if ( PCI_SLOT(devfn) != PCI_SLOT(pdev->devfn) )
             break;
-        ret = hd->platform_ops->reassign_device(d, target, devfn,
-                                                pci_to_dev(pdev));
+        ret = iommu_call(hd->platform_ops, reassign_device, d, target, devfn,
+                         pci_to_dev(pdev));
         if ( ret )
             goto out;
     }
 
     devfn = pdev->devfn;
-    ret = hd->platform_ops->reassign_device(d, target, devfn,
-                                            pci_to_dev(pdev));
+    ret = iommu_call(hd->platform_ops, reassign_device, d, target, devfn,
+                     pci_to_dev(pdev));
     if ( ret )
         goto out;
 
@@ -1300,7 +1300,7 @@  static int iommu_add_device(struct pci_d
 {
     const struct domain_iommu *hd;
     int rc;
-    u8 devfn;
+    unsigned int devfn = pdev->devfn;
 
     if ( !pdev->domain )
         return -EINVAL;
@@ -1311,16 +1311,16 @@  static int iommu_add_device(struct pci_d
     if ( !is_iommu_enabled(pdev->domain) )
         return 0;
 
-    rc = hd->platform_ops->add_device(pdev->devfn, pci_to_dev(pdev));
+    rc = iommu_call(hd->platform_ops, add_device, devfn, pci_to_dev(pdev));
     if ( rc || !pdev->phantom_stride )
         return rc;
 
-    for ( devfn = pdev->devfn ; ; )
+    for ( ; ; )
     {
         devfn += pdev->phantom_stride;
         if ( PCI_SLOT(devfn) != PCI_SLOT(pdev->devfn) )
             return 0;
-        rc = hd->platform_ops->add_device(devfn, pci_to_dev(pdev));
+        rc = iommu_call(hd->platform_ops, add_device, devfn, pci_to_dev(pdev));
         if ( rc )
             printk(XENLOG_WARNING "IOMMU: add %pp failed (%d)\n",
                    &pdev->sbdf, rc);
@@ -1341,7 +1341,7 @@  static int iommu_enable_device(struct pc
          !hd->platform_ops->enable_device )
         return 0;
 
-    return hd->platform_ops->enable_device(pci_to_dev(pdev));
+    return iommu_call(hd->platform_ops, enable_device, pci_to_dev(pdev));
 }
 
 static int iommu_remove_device(struct pci_dev *pdev)
@@ -1363,7 +1363,8 @@  static int iommu_remove_device(struct pc
         devfn += pdev->phantom_stride;
         if ( PCI_SLOT(devfn) != PCI_SLOT(pdev->devfn) )
             break;
-        rc = hd->platform_ops->remove_device(devfn, pci_to_dev(pdev));
+        rc = iommu_call(hd->platform_ops, remove_device, devfn,
+                        pci_to_dev(pdev));
         if ( !rc )
             continue;
 
@@ -1371,7 +1372,9 @@  static int iommu_remove_device(struct pc
         return rc;
     }
 
-    return hd->platform_ops->remove_device(pdev->devfn, pci_to_dev(pdev));
+    devfn = pdev->devfn;
+
+    return iommu_call(hd->platform_ops, remove_device, devfn, pci_to_dev(pdev));
 }
 
 static int device_assigned(u16 seg, u8 bus, u8 devfn)
@@ -1421,7 +1424,8 @@  static int assign_device(struct domain *
 
     pdev->fault.count = 0;
 
-    if ( (rc = hd->platform_ops->assign_device(d, devfn, pci_to_dev(pdev), flag)) )
+    if ( (rc = iommu_call(hd->platform_ops, assign_device, d, devfn,
+                          pci_to_dev(pdev), flag)) )
         goto done;
 
     for ( ; pdev->phantom_stride; rc = 0 )
@@ -1429,7 +1433,8 @@  static int assign_device(struct domain *
         devfn += pdev->phantom_stride;
         if ( PCI_SLOT(devfn) != PCI_SLOT(pdev->devfn) )
             break;
-        rc = hd->platform_ops->assign_device(d, devfn, pci_to_dev(pdev), flag);
+        rc = iommu_call(hd->platform_ops, assign_device, d, devfn,
+                        pci_to_dev(pdev), flag);
     }
 
  done:
@@ -1457,24 +1462,24 @@  static int iommu_get_device_group(
     if ( !is_iommu_enabled(d) || !ops->get_device_group_id )
         return 0;
 
-    group_id = ops->get_device_group_id(seg, bus, devfn);
+    group_id = iommu_call(ops, get_device_group_id, seg, bus, devfn);
 
     pcidevs_lock();
     for_each_pdev( d, pdev )
     {
-        if ( (pdev->seg != seg) ||
-             ((pdev->bus == bus) && (pdev->devfn == devfn)) )
+        unsigned int b = pdev->bus;
+        unsigned int df = pdev->devfn;
+
+        if ( (pdev->seg != seg) || ((b == bus) && (df == devfn)) )
             continue;
 
-        if ( xsm_get_device_group(XSM_HOOK, (seg << 16) | (pdev->bus << 8) | pdev->devfn) )
+        if ( xsm_get_device_group(XSM_HOOK, (seg << 16) | (b << 8) | df) )
             continue;
 
-        sdev_id = ops->get_device_group_id(seg, pdev->bus, pdev->devfn);
+        sdev_id = iommu_call(ops, get_device_group_id, seg, b, df);
         if ( (sdev_id == group_id) && (i < max_sdevs) )
         {
-            bdf = 0;
-            bdf |= (pdev->bus & 0xff) << 16;
-            bdf |= (pdev->devfn & 0xff) << 8;
+            bdf = (b << 16) | (df << 8);
 
             if ( unlikely(copy_to_guest_offset(buf, i, &bdf, 1)) )
             {
--- a/xen/drivers/passthrough/x86/iommu.c
+++ b/xen/drivers/passthrough/x86/iommu.c
@@ -145,7 +145,7 @@  unsigned int iommu_read_apic_from_ire(un
 int __init iommu_setup_hpet_msi(struct msi_desc *msi)
 {
     const struct iommu_ops *ops = iommu_get_ops();
-    return ops->setup_hpet_msi ? ops->setup_hpet_msi(msi) : -ENODEV;
+    return ops->setup_hpet_msi ? iommu_call(ops, setup_hpet_msi, msi) : -ENODEV;
 }
 
 void __hwdom_init arch_iommu_check_autotranslated_hwdom(struct domain *d)
@@ -406,7 +406,7 @@  int iommu_free_pgtables(struct domain *d
      * Pages will be moved to the free list below. So we want to
      * clear the root page-table to avoid any potential use after-free.
      */
-    hd->platform_ops->clear_root_pgtable(d);
+    iommu_vcall(hd->platform_ops, clear_root_pgtable, d);
 
     while ( (pg = page_list_remove_head(&hd->arch.pgtables.list)) )
     {