[PATCH for-4.12] xen/iommu: fix dev assignment on ARM after 91d4eca7

[PATCH for-4.12] xen/iommu: fix dev assignment on ARM after 91d4eca7

[Stefano Stabellini]

Fix device assignment on ARM after 91d4eca7 "mm / iommu: split
need_iommu() into has_iommu_pt() and need_iommu_pt_sync()".

arch_iommu_populate_page_table returns -ENOSYS which causes
iommu_construct to return early, although it is not an error.

Interestingly, the if ( rc ) was present even before 91d4eca7, but it was
still working before. Now, with the new hd->status field it won't
complete the initialization successfully.

Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>

diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index ac62d7f..a63329b 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -269,7 +269,7 @@ int iommu_construct(struct domain *d)
         hd->need_sync = true;
 
         rc = arch_iommu_populate_page_table(d);
-        if ( rc )
+        if ( rc != 0 && rc != -ENOSYS )
         {
             if ( rc != -ERESTART )
             {

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Re: [PATCH for-4.12] xen/iommu: fix dev assignment on ARM after 91d4eca7

[Andrew Cooper]

On 03/01/2019 00:28, Stefano Stabellini wrote:
> Fix device assignment on ARM after 91d4eca7 "mm / iommu: split
> need_iommu() into has_iommu_pt() and need_iommu_pt_sync()".
>
> arch_iommu_populate_page_table returns -ENOSYS which causes
> iommu_construct to return early, although it is not an error.
>
> Interestingly, the if ( rc ) was present even before 91d4eca7, but it was
> still working before. Now, with the new hd->status field it won't
> complete the initialization successfully.
>
> Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
>
> diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
> index ac62d7f..a63329b 100644
> --- a/xen/drivers/passthrough/iommu.c
> +++ b/xen/drivers/passthrough/iommu.c
> @@ -269,7 +269,7 @@ int iommu_construct(struct domain *d)
>          hd->need_sync = true;
>  
>          rc = arch_iommu_populate_page_table(d);

The comment in ARM's arch_iommu_populate_page_table() says

/* The IOMMU shares the p2m with the CPU */

Which means that iommu_use_hap_pt() (just out of context above this
hunk) is wrong.  It should return true, which will prevent us entering
this path during initialisation.

~Andrew

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Re: [PATCH for-4.12] xen/iommu: fix dev assignment on ARM after 91d4eca7

[Stefano Stabellini]

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On Thu, 3 Jan 2019, Andrew Cooper wrote:
> On 03/01/2019 00:28, Stefano Stabellini wrote:
> > Fix device assignment on ARM after 91d4eca7 "mm / iommu: split
> > need_iommu() into has_iommu_pt() and need_iommu_pt_sync()".
> >
> > arch_iommu_populate_page_table returns -ENOSYS which causes
> > iommu_construct to return early, although it is not an error.
> >
> > Interestingly, the if ( rc ) was present even before 91d4eca7, but it was
> > still working before. Now, with the new hd->status field it won't
> > complete the initialization successfully.
> >
> > Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
> >
> > diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
> > index ac62d7f..a63329b 100644
> > --- a/xen/drivers/passthrough/iommu.c
> > +++ b/xen/drivers/passthrough/iommu.c
> > @@ -269,7 +269,7 @@ int iommu_construct(struct domain *d)
> >          hd->need_sync = true;
> >  
> >          rc = arch_iommu_populate_page_table(d);
> 
> The comment in ARM's arch_iommu_populate_page_table() says
> 
> /* The IOMMU shares the p2m with the CPU */
> 
> Which means that iommu_use_hap_pt() (just out of context above this
> hunk) is wrong.  It should return true, which will prevent us entering
> this path during initialisation.

iommu_use_hap_pt is implemented by calling has_iommu_pt(d) (also on x86
is part of the implementation), which is implemented as:

  (dom_iommu(d)->status != IOMMU_STATUS_disabled)

IOMMU_STATUS_disabled is zero in the enum, so status starts as
IOMMU_STATUS_disabled. It is set to IOMMU_STATUS_initializing for dom0
in iommu_hwdom_init, but it is not set to IOMMU_STATUS_initializing for
other domains anywhere, leading to this error.

It looks like we want to move the initialization of status from
iommu_hwdom_init to iommu_domain_init, which is called for everybody.


diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index ac62d7f..7cf6aaf 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -180,6 +180,7 @@ int iommu_domain_init(struct domain *d)
     if ( !iommu_enabled )
         return 0;
 
+    hd->status = IOMMU_STATUS_initializing;
     hd->platform_ops = iommu_get_ops();
     return hd->platform_ops->init(d);
 }
@@ -206,7 +207,6 @@ void __hwdom_init iommu_hwdom_init(struct domain *d)
 
     register_keyhandler('o', &iommu_dump_p2m_table, "dump iommu p2m table", 0);
 
-    hd->status = IOMMU_STATUS_initializing;
     hd->need_sync = iommu_hwdom_strict && !iommu_use_hap_pt(d);
     if ( need_iommu_pt_sync(d) )
     {

[-- Attachment #2: Type: text/plain, Size: 157 bytes --]

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Re: [PATCH for-4.12] xen/iommu: fix dev assignment on ARM after 91d4eca7

[Paul Durrant]

> -----Original Message-----
> From: Stefano Stabellini [mailto:sstabellini@kernel.org]
> Sent: 03 January 2019 18:20
> To: Andrew Cooper <Andrew.Cooper3@citrix.com>
> Cc: Stefano Stabellini <sstabellini@kernel.org>; xen-devel@lists.xen.org;
> julien.grall@arm.com; jbeulich@suse.com; Paul Durrant
> <Paul.Durrant@citrix.com>
> Subject: Re: [Xen-devel] [PATCH for-4.12] xen/iommu: fix dev assignment on
> ARM after 91d4eca7
> 
> On Thu, 3 Jan 2019, Andrew Cooper wrote:
> > On 03/01/2019 00:28, Stefano Stabellini wrote:
> > > Fix device assignment on ARM after 91d4eca7 "mm / iommu: split
> > > need_iommu() into has_iommu_pt() and need_iommu_pt_sync()".
> > >
> > > arch_iommu_populate_page_table returns -ENOSYS which causes
> > > iommu_construct to return early, although it is not an error.
> > >
> > > Interestingly, the if ( rc ) was present even before 91d4eca7, but it
> was
> > > still working before. Now, with the new hd->status field it won't
> > > complete the initialization successfully.
> > >
> > > Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
> > >
> > > diff --git a/xen/drivers/passthrough/iommu.c
> b/xen/drivers/passthrough/iommu.c
> > > index ac62d7f..a63329b 100644
> > > --- a/xen/drivers/passthrough/iommu.c
> > > +++ b/xen/drivers/passthrough/iommu.c
> > > @@ -269,7 +269,7 @@ int iommu_construct(struct domain *d)
> > >          hd->need_sync = true;
> > >
> > >          rc = arch_iommu_populate_page_table(d);
> >
> > The comment in ARM's arch_iommu_populate_page_table() says
> >
> > /* The IOMMU shares the p2m with the CPU */
> >
> > Which means that iommu_use_hap_pt() (just out of context above this
> > hunk) is wrong.  It should return true, which will prevent us entering
> > this path during initialisation.
> 
> iommu_use_hap_pt is implemented by calling has_iommu_pt(d) (also on x86
> is part of the implementation), which is implemented as:
> 
>   (dom_iommu(d)->status != IOMMU_STATUS_disabled)
> 
> IOMMU_STATUS_disabled is zero in the enum, so status starts as
> IOMMU_STATUS_disabled. It is set to IOMMU_STATUS_initializing for dom0
> in iommu_hwdom_init, but it is not set to IOMMU_STATUS_initializing for
> other domains anywhere, leading to this error.

It is set for other domains... see iommu_construct().

  Paul

> 
> It looks like we want to move the initialization of status from
> iommu_hwdom_init to iommu_domain_init, which is called for everybody.
> 
> 
> diff --git a/xen/drivers/passthrough/iommu.c
> b/xen/drivers/passthrough/iommu.c
> index ac62d7f..7cf6aaf 100644
> --- a/xen/drivers/passthrough/iommu.c
> +++ b/xen/drivers/passthrough/iommu.c
> @@ -180,6 +180,7 @@ int iommu_domain_init(struct domain *d)
>      if ( !iommu_enabled )
>          return 0;
> 
> +    hd->status = IOMMU_STATUS_initializing;
>      hd->platform_ops = iommu_get_ops();
>      return hd->platform_ops->init(d);
>  }
> @@ -206,7 +207,6 @@ void __hwdom_init iommu_hwdom_init(struct domain *d)
> 
>      register_keyhandler('o', &iommu_dump_p2m_table, "dump iommu p2m
> table", 0);
> 
> -    hd->status = IOMMU_STATUS_initializing;
>      hd->need_sync = iommu_hwdom_strict && !iommu_use_hap_pt(d);
>      if ( need_iommu_pt_sync(d) )
>      {
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Re: [PATCH for-4.12] xen/iommu: fix dev assignment on ARM after 91d4eca7

[Stefano Stabellini]

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On Fri, 4 Jan 2019, Paul Durrant wrote:
> > -----Original Message-----
> > From: Stefano Stabellini [mailto:sstabellini@kernel.org]
> > Sent: 03 January 2019 18:20
> > To: Andrew Cooper <Andrew.Cooper3@citrix.com>
> > Cc: Stefano Stabellini <sstabellini@kernel.org>; xen-devel@lists.xen.org;
> > julien.grall@arm.com; jbeulich@suse.com; Paul Durrant
> > <Paul.Durrant@citrix.com>
> > Subject: Re: [Xen-devel] [PATCH for-4.12] xen/iommu: fix dev assignment on
> > ARM after 91d4eca7
> > 
> > On Thu, 3 Jan 2019, Andrew Cooper wrote:
> > > On 03/01/2019 00:28, Stefano Stabellini wrote:
> > > > Fix device assignment on ARM after 91d4eca7 "mm / iommu: split
> > > > need_iommu() into has_iommu_pt() and need_iommu_pt_sync()".
> > > >
> > > > arch_iommu_populate_page_table returns -ENOSYS which causes
> > > > iommu_construct to return early, although it is not an error.
> > > >
> > > > Interestingly, the if ( rc ) was present even before 91d4eca7, but it
> > was
> > > > still working before. Now, with the new hd->status field it won't
> > > > complete the initialization successfully.
> > > >
> > > > Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
> > > >
> > > > diff --git a/xen/drivers/passthrough/iommu.c
> > b/xen/drivers/passthrough/iommu.c
> > > > index ac62d7f..a63329b 100644
> > > > --- a/xen/drivers/passthrough/iommu.c
> > > > +++ b/xen/drivers/passthrough/iommu.c
> > > > @@ -269,7 +269,7 @@ int iommu_construct(struct domain *d)
> > > >          hd->need_sync = true;
> > > >
> > > >          rc = arch_iommu_populate_page_table(d);
> > >
> > > The comment in ARM's arch_iommu_populate_page_table() says
> > >
> > > /* The IOMMU shares the p2m with the CPU */
> > >
> > > Which means that iommu_use_hap_pt() (just out of context above this
> > > hunk) is wrong.  It should return true, which will prevent us entering
> > > this path during initialisation.
> > 
> > iommu_use_hap_pt is implemented by calling has_iommu_pt(d) (also on x86
> > is part of the implementation), which is implemented as:
> > 
> >   (dom_iommu(d)->status != IOMMU_STATUS_disabled)
> > 
> > IOMMU_STATUS_disabled is zero in the enum, so status starts as
> > IOMMU_STATUS_disabled. It is set to IOMMU_STATUS_initializing for dom0
> > in iommu_hwdom_init, but it is not set to IOMMU_STATUS_initializing for
> > other domains anywhere, leading to this error.
> 
> It is set for other domains... see iommu_construct().

Hi Paul, unfortunately it doesn't work that way. Let me explain:


iommu_construct() sets hd->status to IOMMU_STATUS_initializing *after*
calling iommu_use_hap_pt(d), and specifically inside the if statement:

    if ( !iommu_use_hap_pt(d) )
    {
        int rc;

        hd->status = IOMMU_STATUS_initializing;
        hd->need_sync = true;

        rc = arch_iommu_populate_page_table(d);
        if ( rc )
        {
            if ( rc != -ERESTART )
            {
                hd->need_sync = false;
                hd->status = IOMMU_STATUS_disabled;
            }

            return rc;
        }
    }

However, for iommu_use_hap_pt(d) to return the correct value, which
should be always true on ARM, status needs to be already set to
IOMMU_STATUS_initializing.

Because when we enter iommu_construct status is IOMMU_STATUS_disabled,
iommu_use_hap_pt(d) calls has_iommu_pt(d) which wrongly returns false
because it is implemented as:

#define has_iommu_pt(d) (dom_iommu(d)->status != IOMMU_STATUS_disabled)


I think we need to move the initialization of status to
IOMMU_STATUS_initializing earlier, specifically to iommu_domain_init.

[-- Attachment #2: Type: text/plain, Size: 157 bytes --]

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Re: [PATCH for-4.12] xen/iommu: fix dev assignment on ARM after 91d4eca7

[Paul Durrant]

> -----Original Message-----
> From: Stefano Stabellini [mailto:sstabellini@kernel.org]
> Sent: 04 January 2019 17:46
> To: Paul Durrant <Paul.Durrant@citrix.com>
> Cc: 'Stefano Stabellini' <sstabellini@kernel.org>; Andrew Cooper
> <Andrew.Cooper3@citrix.com>; xen-devel@lists.xen.org;
> julien.grall@arm.com; jbeulich@suse.com
> Subject: RE: [Xen-devel] [PATCH for-4.12] xen/iommu: fix dev assignment on
> ARM after 91d4eca7
> 
> On Fri, 4 Jan 2019, Paul Durrant wrote:
> > > -----Original Message-----
> > > From: Stefano Stabellini [mailto:sstabellini@kernel.org]
> > > Sent: 03 January 2019 18:20
> > > To: Andrew Cooper <Andrew.Cooper3@citrix.com>
> > > Cc: Stefano Stabellini <sstabellini@kernel.org>; xen-
> devel@lists.xen.org;
> > > julien.grall@arm.com; jbeulich@suse.com; Paul Durrant
> > > <Paul.Durrant@citrix.com>
> > > Subject: Re: [Xen-devel] [PATCH for-4.12] xen/iommu: fix dev
> assignment on
> > > ARM after 91d4eca7
> > >
> > > On Thu, 3 Jan 2019, Andrew Cooper wrote:
> > > > On 03/01/2019 00:28, Stefano Stabellini wrote:
> > > > > Fix device assignment on ARM after 91d4eca7 "mm / iommu: split
> > > > > need_iommu() into has_iommu_pt() and need_iommu_pt_sync()".
> > > > >
> > > > > arch_iommu_populate_page_table returns -ENOSYS which causes
> > > > > iommu_construct to return early, although it is not an error.
> > > > >
> > > > > Interestingly, the if ( rc ) was present even before 91d4eca7, but
> it
> > > was
> > > > > still working before. Now, with the new hd->status field it won't
> > > > > complete the initialization successfully.
> > > > >
> > > > > Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
> > > > >
> > > > > diff --git a/xen/drivers/passthrough/iommu.c
> > > b/xen/drivers/passthrough/iommu.c
> > > > > index ac62d7f..a63329b 100644
> > > > > --- a/xen/drivers/passthrough/iommu.c
> > > > > +++ b/xen/drivers/passthrough/iommu.c
> > > > > @@ -269,7 +269,7 @@ int iommu_construct(struct domain *d)
> > > > >          hd->need_sync = true;
> > > > >
> > > > >          rc = arch_iommu_populate_page_table(d);
> > > >
> > > > The comment in ARM's arch_iommu_populate_page_table() says
> > > >
> > > > /* The IOMMU shares the p2m with the CPU */
> > > >
> > > > Which means that iommu_use_hap_pt() (just out of context above this
> > > > hunk) is wrong.  It should return true, which will prevent us
> entering
> > > > this path during initialisation.
> > >
> > > iommu_use_hap_pt is implemented by calling has_iommu_pt(d) (also on
> x86
> > > is part of the implementation), which is implemented as:
> > >
> > >   (dom_iommu(d)->status != IOMMU_STATUS_disabled)
> > >
> > > IOMMU_STATUS_disabled is zero in the enum, so status starts as
> > > IOMMU_STATUS_disabled. It is set to IOMMU_STATUS_initializing for dom0
> > > in iommu_hwdom_init, but it is not set to IOMMU_STATUS_initializing
> for
> > > other domains anywhere, leading to this error.
> >
> > It is set for other domains... see iommu_construct().
> 
> Hi Paul, unfortunately it doesn't work that way. Let me explain:
> 
> 
> iommu_construct() sets hd->status to IOMMU_STATUS_initializing *after*
> calling iommu_use_hap_pt(d), and specifically inside the if statement:
> 
>     if ( !iommu_use_hap_pt(d) )
>     {
>         int rc;
> 
>         hd->status = IOMMU_STATUS_initializing;
>         hd->need_sync = true;
> 
>         rc = arch_iommu_populate_page_table(d);
>         if ( rc )
>         {
>             if ( rc != -ERESTART )
>             {
>                 hd->need_sync = false;
>                 hd->status = IOMMU_STATUS_disabled;
>             }
> 
>             return rc;
>         }
>     }
> 
> However, for iommu_use_hap_pt(d) to return the correct value, which
> should be always true on ARM, status needs to be already set to
> IOMMU_STATUS_initializing.
> 
> Because when we enter iommu_construct status is IOMMU_STATUS_disabled,
> iommu_use_hap_pt(d) calls has_iommu_pt(d) which wrongly returns false
> because it is implemented as:
> 
> #define has_iommu_pt(d) (dom_iommu(d)->status != IOMMU_STATUS_disabled)
> 
> 
> I think we need to move the initialization of status to
> IOMMU_STATUS_initializing earlier, specifically to iommu_domain_init.

The use of iommu_use_hap_pt() here is indeed a problem, but I think it would be sufficient to move the line "hd->status = IOMMU_STATUS_initializing" to just before the if rather than to a completely separate function.

  Paul

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Re: [PATCH for-4.12] xen/iommu: fix dev assignment on ARM after 91d4eca7

[Stefano Stabellini]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 5759 bytes --]

On Mon, 7 Jan 2019, Paul Durrant wrote:
> > -----Original Message-----
> > From: Stefano Stabellini [mailto:sstabellini@kernel.org]
> > Sent: 04 January 2019 17:46
> > To: Paul Durrant <Paul.Durrant@citrix.com>
> > Cc: 'Stefano Stabellini' <sstabellini@kernel.org>; Andrew Cooper
> > <Andrew.Cooper3@citrix.com>; xen-devel@lists.xen.org;
> > julien.grall@arm.com; jbeulich@suse.com
> > Subject: RE: [Xen-devel] [PATCH for-4.12] xen/iommu: fix dev assignment on
> > ARM after 91d4eca7
> > 
> > On Fri, 4 Jan 2019, Paul Durrant wrote:
> > > > -----Original Message-----
> > > > From: Stefano Stabellini [mailto:sstabellini@kernel.org]
> > > > Sent: 03 January 2019 18:20
> > > > To: Andrew Cooper <Andrew.Cooper3@citrix.com>
> > > > Cc: Stefano Stabellini <sstabellini@kernel.org>; xen-
> > devel@lists.xen.org;
> > > > julien.grall@arm.com; jbeulich@suse.com; Paul Durrant
> > > > <Paul.Durrant@citrix.com>
> > > > Subject: Re: [Xen-devel] [PATCH for-4.12] xen/iommu: fix dev
> > assignment on
> > > > ARM after 91d4eca7
> > > >
> > > > On Thu, 3 Jan 2019, Andrew Cooper wrote:
> > > > > On 03/01/2019 00:28, Stefano Stabellini wrote:
> > > > > > Fix device assignment on ARM after 91d4eca7 "mm / iommu: split
> > > > > > need_iommu() into has_iommu_pt() and need_iommu_pt_sync()".
> > > > > >
> > > > > > arch_iommu_populate_page_table returns -ENOSYS which causes
> > > > > > iommu_construct to return early, although it is not an error.
> > > > > >
> > > > > > Interestingly, the if ( rc ) was present even before 91d4eca7, but
> > it
> > > > was
> > > > > > still working before. Now, with the new hd->status field it won't
> > > > > > complete the initialization successfully.
> > > > > >
> > > > > > Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
> > > > > >
> > > > > > diff --git a/xen/drivers/passthrough/iommu.c
> > > > b/xen/drivers/passthrough/iommu.c
> > > > > > index ac62d7f..a63329b 100644
> > > > > > --- a/xen/drivers/passthrough/iommu.c
> > > > > > +++ b/xen/drivers/passthrough/iommu.c
> > > > > > @@ -269,7 +269,7 @@ int iommu_construct(struct domain *d)
> > > > > >          hd->need_sync = true;
> > > > > >
> > > > > >          rc = arch_iommu_populate_page_table(d);
> > > > >
> > > > > The comment in ARM's arch_iommu_populate_page_table() says
> > > > >
> > > > > /* The IOMMU shares the p2m with the CPU */
> > > > >
> > > > > Which means that iommu_use_hap_pt() (just out of context above this
> > > > > hunk) is wrong.  It should return true, which will prevent us
> > entering
> > > > > this path during initialisation.
> > > >
> > > > iommu_use_hap_pt is implemented by calling has_iommu_pt(d) (also on
> > x86
> > > > is part of the implementation), which is implemented as:
> > > >
> > > >   (dom_iommu(d)->status != IOMMU_STATUS_disabled)
> > > >
> > > > IOMMU_STATUS_disabled is zero in the enum, so status starts as
> > > > IOMMU_STATUS_disabled. It is set to IOMMU_STATUS_initializing for dom0
> > > > in iommu_hwdom_init, but it is not set to IOMMU_STATUS_initializing
> > for
> > > > other domains anywhere, leading to this error.
> > >
> > > It is set for other domains... see iommu_construct().
> > 
> > Hi Paul, unfortunately it doesn't work that way. Let me explain:
> > 
> > 
> > iommu_construct() sets hd->status to IOMMU_STATUS_initializing *after*
> > calling iommu_use_hap_pt(d), and specifically inside the if statement:
> > 
> >     if ( !iommu_use_hap_pt(d) )
> >     {
> >         int rc;
> > 
> >         hd->status = IOMMU_STATUS_initializing;
> >         hd->need_sync = true;
> > 
> >         rc = arch_iommu_populate_page_table(d);
> >         if ( rc )
> >         {
> >             if ( rc != -ERESTART )
> >             {
> >                 hd->need_sync = false;
> >                 hd->status = IOMMU_STATUS_disabled;
> >             }
> > 
> >             return rc;
> >         }
> >     }
> > 
> > However, for iommu_use_hap_pt(d) to return the correct value, which
> > should be always true on ARM, status needs to be already set to
> > IOMMU_STATUS_initializing.
> > 
> > Because when we enter iommu_construct status is IOMMU_STATUS_disabled,
> > iommu_use_hap_pt(d) calls has_iommu_pt(d) which wrongly returns false
> > because it is implemented as:
> > 
> > #define has_iommu_pt(d) (dom_iommu(d)->status != IOMMU_STATUS_disabled)
> > 
> > 
> > I think we need to move the initialization of status to
> > IOMMU_STATUS_initializing earlier, specifically to iommu_domain_init.
> 
> The use of iommu_use_hap_pt() here is indeed a problem, but I think it would be sufficient to move the line "hd->status = IOMMU_STATUS_initializing" to just before the if rather than to a completely separate function.

Yes, that works too.
 
---
xen/iommu: fix dev assignment on ARM after 91d4eca7

Fix device assignment on ARM after 91d4eca7 "mm / iommu: split
need_iommu() into has_iommu_pt() and need_iommu_pt_sync()".

arch_iommu_populate_page_table returns -ENOSYS which causes
iommu_construct to return early, although it is not an error.

hd->status needs to be set to IOMMU_STATUS_initializing before calling
iommu_use_hap_pt, otherwise iommu_use_hap_pt will return the wrong
value.

Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>

diff --git a/xen/drivers/passthrough/iommu.c b/xen/drivers/passthrough/iommu.c
index ac62d7f..a6f69f4 100644
--- a/xen/drivers/passthrough/iommu.c
+++ b/xen/drivers/passthrough/iommu.c
@@ -261,11 +261,11 @@ int iommu_construct(struct domain *d)
     if ( hd->status == IOMMU_STATUS_initialized )
         return 0;
 
+    hd->status = IOMMU_STATUS_initializing;
     if ( !iommu_use_hap_pt(d) )
     {
         int rc;
 
-        hd->status = IOMMU_STATUS_initializing;
         hd->need_sync = true;
 
         rc = arch_iommu_populate_page_table(d);

[-- Attachment #2: Type: text/plain, Size: 157 bytes --]

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Re: [PATCH for-4.12] xen/iommu: fix dev assignment on ARM after 91d4eca7

[Paul Durrant]

> -----Original Message-----
[snip]
> >
> > The use of iommu_use_hap_pt() here is indeed a problem, but I think it
> would be sufficient to move the line "hd->status =
> IOMMU_STATUS_initializing" to just before the if rather than to a
> completely separate function.
> 
> Yes, that works too.
> 
> ---
> xen/iommu: fix dev assignment on ARM after 91d4eca7
> 
> Fix device assignment on ARM after 91d4eca7 "mm / iommu: split
> need_iommu() into has_iommu_pt() and need_iommu_pt_sync()".
> 
> arch_iommu_populate_page_table returns -ENOSYS which causes
> iommu_construct to return early, although it is not an error.
> 
> hd->status needs to be set to IOMMU_STATUS_initializing before calling
> iommu_use_hap_pt, otherwise iommu_use_hap_pt will return the wrong
> value.
> 
> Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>

LGTM so you can add...

Reviewed-by: Paul Durrant <paul.durrant@citrix.com>

> 
> diff --git a/xen/drivers/passthrough/iommu.c
> b/xen/drivers/passthrough/iommu.c
> index ac62d7f..a6f69f4 100644
> --- a/xen/drivers/passthrough/iommu.c
> +++ b/xen/drivers/passthrough/iommu.c
> @@ -261,11 +261,11 @@ int iommu_construct(struct domain *d)
>      if ( hd->status == IOMMU_STATUS_initialized )
>          return 0;
> 
> +    hd->status = IOMMU_STATUS_initializing;
>      if ( !iommu_use_hap_pt(d) )
>      {
>          int rc;
> 
> -        hd->status = IOMMU_STATUS_initializing;
>          hd->need_sync = true;
> 
>          rc = arch_iommu_populate_page_table(d);
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Re: [PATCH for-4.12] xen/iommu: fix dev assignment on ARM after 91d4eca7

[Jan Beulich]

>>> On 08.01.19 at 09:30, <Paul.Durrant@citrix.com> wrote:
>>  -----Original Message-----
> [snip]
>> >
>> > The use of iommu_use_hap_pt() here is indeed a problem, but I think it
>> would be sufficient to move the line "hd->status =
>> IOMMU_STATUS_initializing" to just before the if rather than to a
>> completely separate function.
>> 
>> Yes, that works too.
>> 
>> ---
>> xen/iommu: fix dev assignment on ARM after 91d4eca7
>> 
>> Fix device assignment on ARM after 91d4eca7 "mm / iommu: split
>> need_iommu() into has_iommu_pt() and need_iommu_pt_sync()".
>> 
>> arch_iommu_populate_page_table returns -ENOSYS which causes
>> iommu_construct to return early, although it is not an error.
>> 
>> hd->status needs to be set to IOMMU_STATUS_initializing before calling
>> iommu_use_hap_pt, otherwise iommu_use_hap_pt will return the wrong
>> value.
>> 
>> Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
> 
> LGTM so you can add...
> 
> Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
> 
>> 
>> diff --git a/xen/drivers/passthrough/iommu.c
>> b/xen/drivers/passthrough/iommu.c
>> index ac62d7f..a6f69f4 100644
>> --- a/xen/drivers/passthrough/iommu.c
>> +++ b/xen/drivers/passthrough/iommu.c
>> @@ -261,11 +261,11 @@ int iommu_construct(struct domain *d)
>>      if ( hd->status == IOMMU_STATUS_initialized )
>>          return 0;
>> 
>> +    hd->status = IOMMU_STATUS_initializing;
>>      if ( !iommu_use_hap_pt(d) )

With a blank line inserted above here also
Acked-by: Jan Beulich <jbeulich@suse.com>

Jan



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Re: [PATCH for-4.12] xen/iommu: fix dev assignment on ARM after 91d4eca7

[Stefano Stabellini]

On Tue, 8 Jan 2019, Jan Beulich wrote:
> >>> On 08.01.19 at 09:30, <Paul.Durrant@citrix.com> wrote:
> >>  -----Original Message-----
> > [snip]
> >> >
> >> > The use of iommu_use_hap_pt() here is indeed a problem, but I think it
> >> would be sufficient to move the line "hd->status =
> >> IOMMU_STATUS_initializing" to just before the if rather than to a
> >> completely separate function.
> >> 
> >> Yes, that works too.
> >> 
> >> ---
> >> xen/iommu: fix dev assignment on ARM after 91d4eca7
> >> 
> >> Fix device assignment on ARM after 91d4eca7 "mm / iommu: split
> >> need_iommu() into has_iommu_pt() and need_iommu_pt_sync()".
> >> 
> >> arch_iommu_populate_page_table returns -ENOSYS which causes
> >> iommu_construct to return early, although it is not an error.
> >> 
> >> hd->status needs to be set to IOMMU_STATUS_initializing before calling
> >> iommu_use_hap_pt, otherwise iommu_use_hap_pt will return the wrong
> >> value.
> >> 
> >> Signed-off-by: Stefano Stabellini <stefanos@xilinx.com>
> > 
> > LGTM so you can add...
> > 
> > Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
> > 
> >> 
> >> diff --git a/xen/drivers/passthrough/iommu.c
> >> b/xen/drivers/passthrough/iommu.c
> >> index ac62d7f..a6f69f4 100644
> >> --- a/xen/drivers/passthrough/iommu.c
> >> +++ b/xen/drivers/passthrough/iommu.c
> >> @@ -261,11 +261,11 @@ int iommu_construct(struct domain *d)
> >>      if ( hd->status == IOMMU_STATUS_initialized )
> >>          return 0;
> >> 
> >> +    hd->status = IOMMU_STATUS_initializing;
> >>      if ( !iommu_use_hap_pt(d) )
> 
> With a blank line inserted above here also
> Acked-by: Jan Beulich <jbeulich@suse.com>

Added and committed. Thanks!

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