[PATCH] x86/MSI-X: correctly track interrupt masking state

[PATCH] x86/MSI-X: correctly track interrupt masking state

[Jan Beulich]

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When a guest unmasks MSI-X interrupts before enabling MSI-X on the
device, so far nothing updates the {host,guest}_masked internal state;
this to date only gets done when MSI-X is already enabled. This is why
half way recent Linux works (as it enables MSI-X first), while Windows
doesn't (as it enables MSI-X only after having set up und unmasked all
vectors). Since with a successful write to the vector control field
everything is ready internally, we should also update internal tracking
state there, regardless of the device's MSI-X enabled state.

Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/msi.c
+++ b/xen/arch/x86/msi.c
@@ -434,8 +434,13 @@ static bool_t msi_set_mask_bit(struct ir
         {
             writel(flag, entry->mask_base + PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET);
             readl(entry->mask_base + PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET);
+
             if ( likely(control & PCI_MSIX_FLAGS_ENABLE) )
                 break;
+
+            entry->msi_attrib.host_masked = host;
+            entry->msi_attrib.guest_masked = guest;
+
             flag = 1;
         }
         else if ( flag && !(control & PCI_MSIX_FLAGS_MASKALL) )




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x86/MSI-X: correctly track interrupt masking state

When a guest unmasks MSI-X interrupts before enabling MSI-X on the
device, so far nothing updates the {host,guest}_masked internal state;
this to date only gets done when MSI-X is already enabled. This is why
half way recent Linux works (as it enables MSI-X first), while Windows
doesn't (as it enables MSI-X only after having set up und unmasked all
vectors). Since with a successful write to the vector control field
everything is ready internally, we should also update internal tracking
state there, regardless of the device's MSI-X enabled state.

Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/xen/arch/x86/msi.c
+++ b/xen/arch/x86/msi.c
@@ -434,8 +434,13 @@ static bool_t msi_set_mask_bit(struct ir
         {
             writel(flag, entry->mask_base + PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET);
             readl(entry->mask_base + PCI_MSIX_ENTRY_VECTOR_CTRL_OFFSET);
+
             if ( likely(control & PCI_MSIX_FLAGS_ENABLE) )
                 break;
+
+            entry->msi_attrib.host_masked = host;
+            entry->msi_attrib.guest_masked = guest;
+
             flag = 1;
         }
         else if ( flag && !(control & PCI_MSIX_FLAGS_MASKALL) )

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Re: [PATCH] x86/MSI-X: correctly track interrupt masking state

[Andrew Cooper]

On 22/04/16 08:20, Jan Beulich wrote:
> When a guest unmasks MSI-X interrupts before enabling MSI-X on the
> device, so far nothing updates the {host,guest}_masked internal state;
> this to date only gets done when MSI-X is already enabled. This is why
> half way recent Linux works (as it enables MSI-X first), while Windows
> doesn't (as it enables MSI-X only after having set up und unmasked all
> vectors). Since with a successful write to the vector control field
> everything is ready internally, we should also update internal tracking
> state there, regardless of the device's MSI-X enabled state.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

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Re: [PATCH] x86/MSI-X: correctly track interrupt masking state

[Jan Beulich]

>>> On 22.04.16 at 18:35, <andrew.cooper3@citrix.com> wrote:
> On 22/04/16 08:20, Jan Beulich wrote:
>> When a guest unmasks MSI-X interrupts before enabling MSI-X on the
>> device, so far nothing updates the {host,guest}_masked internal state;
>> this to date only gets done when MSI-X is already enabled. This is why
>> half way recent Linux works (as it enables MSI-X first), while Windows
>> doesn't (as it enables MSI-X only after having set up und unmasked all
>> vectors). Since with a successful write to the vector control field
>> everything is ready internally, we should also update internal tracking
>> state there, regardless of the device's MSI-X enabled state.
>>
>> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> 
> Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

Wei,

just noticed I forgot to Cc you on this one, which definitely is
intended for 4.7 (along with the other two MSI related ones).

Jan


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Re: [PATCH] x86/MSI-X: correctly track interrupt masking state

[Wei Liu]

On Mon, Apr 25, 2016 at 05:24:43AM -0600, Jan Beulich wrote:
> >>> On 22.04.16 at 18:35, <andrew.cooper3@citrix.com> wrote:
> > On 22/04/16 08:20, Jan Beulich wrote:
> >> When a guest unmasks MSI-X interrupts before enabling MSI-X on the
> >> device, so far nothing updates the {host,guest}_masked internal state;
> >> this to date only gets done when MSI-X is already enabled. This is why
> >> half way recent Linux works (as it enables MSI-X first), while Windows
> >> doesn't (as it enables MSI-X only after having set up und unmasked all
> >> vectors). Since with a successful write to the vector control field
> >> everything is ready internally, we should also update internal tracking
> >> state there, regardless of the device's MSI-X enabled state.
> >>
> >> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> > 
> > Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
> 

Release-acked-by: Wei Liu <wei.liu2@citrix.com>

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