Add a command line opt-in option for posted MSI if CONFIG_X86_POSTED_MSI=y.
Also introduce a helper function for testing if posted MSI is supported on
the platform.
Signed-off-by: Jacob Pan <[email protected]>
---
Documentation/admin-guide/kernel-parameters.txt | 1 +
arch/x86/include/asm/irq_remapping.h | 11 +++++++++++
drivers/iommu/irq_remapping.c | 13 ++++++++++++-
3 files changed, 24 insertions(+), 1 deletion(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index bb884c14b2f6..e5fd02423c4c 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2251,6 +2251,7 @@
no_x2apic_optout
BIOS x2APIC opt-out request will be ignored
nopost disable Interrupt Posting
+ posted_msi enable MSIs delivered as posted interrupts
iomem= Disable strict checking of access to MMIO memory
strict regions from userspace.
diff --git a/arch/x86/include/asm/irq_remapping.h b/arch/x86/include/asm/irq_remapping.h
index 7a2ed154a5e1..e46bde61029b 100644
--- a/arch/x86/include/asm/irq_remapping.h
+++ b/arch/x86/include/asm/irq_remapping.h
@@ -50,6 +50,17 @@ static inline struct irq_domain *arch_get_ir_parent_domain(void)
return x86_vector_domain;
}
+#ifdef CONFIG_X86_POSTED_MSI
+extern int enable_posted_msi;
+
+static inline bool posted_msi_supported(void)
+{
+ return enable_posted_msi && irq_remapping_cap(IRQ_POSTING_CAP);
+}
+#else
+static inline bool posted_msi_supported(void) { return false; };
+#endif
+
#else /* CONFIG_IRQ_REMAP */
static inline bool irq_remapping_cap(enum irq_remap_cap cap) { return 0; }
diff --git a/drivers/iommu/irq_remapping.c b/drivers/iommu/irq_remapping.c
index ee59647c2050..5672783c9f1f 100644
--- a/drivers/iommu/irq_remapping.c
+++ b/drivers/iommu/irq_remapping.c
@@ -24,6 +24,10 @@ int no_x2apic_optout;
int disable_irq_post = 0;
+#ifdef CONFIG_X86_POSTED_MSI
+int enable_posted_msi;
+#endif
+
static int disable_irq_remap;
static struct irq_remap_ops *remap_ops;
@@ -70,7 +74,14 @@ static __init int setup_irqremap(char *str)
no_x2apic_optout = 1;
else if (!strncmp(str, "nopost", 6))
disable_irq_post = 1;
-
+#ifdef CONFIG_X86_POSTED_MSI
+ else if (!strncmp(str, "posted_msi", 10)) {
+ if (disable_irq_post || disable_irq_remap)
+ pr_warn("Posted MSI not enabled due to conflicting options!");
+ else
+ enable_posted_msi = 1;
+ }
+#endif
str += strcspn(str, ",");
while (*str == ',')
str++;
--
2.25.1
On 4/6/2024 6:31 AM, Jacob Pan wrote:
> Add a command line opt-in option for posted MSI if CONFIG_X86_POSTED_MSI=y.
>
> Also introduce a helper function for testing if posted MSI is supported on
> the platform.
>
> Signed-off-by: Jacob Pan <[email protected]>
> ---
> Documentation/admin-guide/kernel-parameters.txt | 1 +
> arch/x86/include/asm/irq_remapping.h | 11 +++++++++++
> drivers/iommu/irq_remapping.c | 13 ++++++++++++-
> 3 files changed, 24 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index bb884c14b2f6..e5fd02423c4c 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -2251,6 +2251,7 @@
> no_x2apic_optout
> BIOS x2APIC opt-out request will be ignored
> nopost disable Interrupt Posting
> + posted_msi enable MSIs delivered as posted interrupts
>
> iomem= Disable strict checking of access to MMIO memory
> strict regions from userspace.
> diff --git a/arch/x86/include/asm/irq_remapping.h b/arch/x86/include/asm/irq_remapping.h
> index 7a2ed154a5e1..e46bde61029b 100644
> --- a/arch/x86/include/asm/irq_remapping.h
> +++ b/arch/x86/include/asm/irq_remapping.h
> @@ -50,6 +50,17 @@ static inline struct irq_domain *arch_get_ir_parent_domain(void)
> return x86_vector_domain;
> }
>
> +#ifdef CONFIG_X86_POSTED_MSI
> +extern int enable_posted_msi;
> +
> +static inline bool posted_msi_supported(void)
> +{
> + return enable_posted_msi && irq_remapping_cap(IRQ_POSTING_CAP);
> +}
Out of this patch set's scope, but, dropping into irq_remappping_cap(), I'd like
to bring this change for discussion:
diff --git a/drivers/iommu/irq_remapping.c b/drivers/iommu/irq_remapping.c
index 4047ac396728..ef2de9034897 100644
--- a/drivers/iommu/irq_remapping.c
+++ b/drivers/iommu/irq_remapping.c
@@ -98,7 +98,7 @@ void set_irq_remapping_broken(void)
bool irq_remapping_cap(enum irq_remap_cap cap)
{
- if (!remap_ops || disable_irq_post)
+ if (!remap_ops || disable_irq_remap)
return false;
return (remap_ops->capability & (1 << cap));
1. irq_remapping_cap() is to exam some cap, though at present it has only 1 cap,
i.e. IRQ_POSTING_CAP, simply return false just because of disable_irq_post isn't
good. Instead, IRQ_REMAP is the foundation of all remapping caps.
2. disable_irq_post is used by Intel iommu code only, here irq_remapping_cap()
is common code. e.g. AMD iommu code doesn't use it to judge set cap of irq_post
or not.
> +#else
> +static inline bool posted_msi_supported(void) { return false; };
> +#endif
Hi Robert,
On Sat, 6 Apr 2024 12:31:14 +0800, Robert Hoo <[email protected]>
wrote:
> On 4/6/2024 6:31 AM, Jacob Pan wrote:
> > Add a command line opt-in option for posted MSI if
> > CONFIG_X86_POSTED_MSI=y.
> >
> > Also introduce a helper function for testing if posted MSI is supported
> > on the platform.
> >
> > Signed-off-by: Jacob Pan <[email protected]>
> > ---
> > Documentation/admin-guide/kernel-parameters.txt | 1 +
> > arch/x86/include/asm/irq_remapping.h | 11 +++++++++++
> > drivers/iommu/irq_remapping.c | 13 ++++++++++++-
> > 3 files changed, 24 insertions(+), 1 deletion(-)
> >
> > diff --git a/Documentation/admin-guide/kernel-parameters.txt
> > b/Documentation/admin-guide/kernel-parameters.txt index
> > bb884c14b2f6..e5fd02423c4c 100644 ---
> > a/Documentation/admin-guide/kernel-parameters.txt +++
> > b/Documentation/admin-guide/kernel-parameters.txt @@ -2251,6 +2251,7 @@
> > no_x2apic_optout
> > BIOS x2APIC opt-out request will be
> > ignored nopost disable Interrupt Posting
> > + posted_msi enable MSIs delivered as posted
> > interrupts
> > iomem= Disable strict checking of access to
> > MMIO memory strict regions from userspace.
> > diff --git a/arch/x86/include/asm/irq_remapping.h
> > b/arch/x86/include/asm/irq_remapping.h index 7a2ed154a5e1..e46bde61029b
> > 100644 --- a/arch/x86/include/asm/irq_remapping.h
> > +++ b/arch/x86/include/asm/irq_remapping.h
> > @@ -50,6 +50,17 @@ static inline struct irq_domain
> > *arch_get_ir_parent_domain(void) return x86_vector_domain;
> > }
> >
> > +#ifdef CONFIG_X86_POSTED_MSI
> > +extern int enable_posted_msi;
> > +
> > +static inline bool posted_msi_supported(void)
> > +{
> > + return enable_posted_msi && irq_remapping_cap(IRQ_POSTING_CAP);
> > +}
>
> Out of this patch set's scope, but, dropping into irq_remappping_cap(),
> I'd like to bring this change for discussion:
>
> diff --git a/drivers/iommu/irq_remapping.c b/drivers/iommu/irq_remapping.c
> index 4047ac396728..ef2de9034897 100644
> --- a/drivers/iommu/irq_remapping.c
> +++ b/drivers/iommu/irq_remapping.c
> @@ -98,7 +98,7 @@ void set_irq_remapping_broken(void)
>
> bool irq_remapping_cap(enum irq_remap_cap cap)
> {
> - if (!remap_ops || disable_irq_post)
> + if (!remap_ops || disable_irq_remap)
> return false;
>
> return (remap_ops->capability & (1 << cap));
>
>
> 1. irq_remapping_cap() is to exam some cap, though at present it has only
> 1 cap, i.e. IRQ_POSTING_CAP, simply return false just because of
> disable_irq_post isn't good. Instead, IRQ_REMAP is the foundation of all
> remapping caps. 2. disable_irq_post is used by Intel iommu code only,
> here irq_remapping_cap() is common code. e.g. AMD iommu code doesn't use
> it to judge set cap of irq_post or not.
I agree, posting should be treated as a sub-capability of remapping.
IRQ_POSTING_CAP is only set when remapping is on.
We need to delete this such that posting is always off when remapping is
off.
--- a/drivers/iommu/intel/irq_remapping.c
+++ b/drivers/iommu/intel/irq_remapping.c
@@ -1038,11 +1038,7 @@ static void disable_irq_remapping(void)
iommu_disable_irq_remapping(iommu);
}
- /*
- * Clear Posted-Interrupts capability.
- */
- if (!disable_irq_post)
- intel_irq_remap_ops.capability &= ~(1 << IRQ_POSTING_CAP);
+ intel_irq_remap_ops.capability &= ~(1 << IRQ_POSTING_CAP);
}
> > +#else
> > +static inline bool posted_msi_supported(void) { return false; };
> > +#endif
>
Thanks,
Jacob
> From: Jacob Pan <[email protected]>
> Sent: Saturday, April 6, 2024 6:31 AM
>
> +#ifdef CONFIG_X86_POSTED_MSI
> + else if (!strncmp(str, "posted_msi", 10)) {
> + if (disable_irq_post || disable_irq_remap)
> + pr_warn("Posted MSI not enabled due to
> conflicting options!");
> + else
> + enable_posted_msi = 1;
> + }
> +#endif
the check of disable_irq_remap is unnecessary. It's unlikely to have
a configuration with disable_irq_post=0 while disable_irq_remap=1
given the latter has bigger scope.
but thinking more do we really need a check here? there is no order
guarantee that "posted_msi" is parsed after the parameters deciding
the value of two disable variables.
it probably makes more sense to just set enable_posted_msi here
and then do all required checks when picking up the irqchip in
intel_irq_remapping_alloc().
On 4/9/2024 7:33 AM, Jacob Pan wrote:
> Hi Robert,
>
> On Sat, 6 Apr 2024 12:31:14 +0800, Robert Hoo <[email protected]>
> wrote:
>
>> On 4/6/2024 6:31 AM, Jacob Pan wrote:
>>> Add a command line opt-in option for posted MSI if
>>> CONFIG_X86_POSTED_MSI=y.
>>>
>>> Also introduce a helper function for testing if posted MSI is supported
>>> on the platform.
>>>
>>> Signed-off-by: Jacob Pan <[email protected]>
>>> ---
>>> Documentation/admin-guide/kernel-parameters.txt | 1 +
>>> arch/x86/include/asm/irq_remapping.h | 11 +++++++++++
>>> drivers/iommu/irq_remapping.c | 13 ++++++++++++-
>>> 3 files changed, 24 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/Documentation/admin-guide/kernel-parameters.txt
>>> b/Documentation/admin-guide/kernel-parameters.txt index
>>> bb884c14b2f6..e5fd02423c4c 100644 ---
>>> a/Documentation/admin-guide/kernel-parameters.txt +++
>>> b/Documentation/admin-guide/kernel-parameters.txt @@ -2251,6 +2251,7 @@
>>> no_x2apic_optout
>>> BIOS x2APIC opt-out request will be
>>> ignored nopost disable Interrupt Posting
>>> + posted_msi enable MSIs delivered as posted
>>> interrupts
>>> iomem= Disable strict checking of access to
>>> MMIO memory strict regions from userspace.
>>> diff --git a/arch/x86/include/asm/irq_remapping.h
>>> b/arch/x86/include/asm/irq_remapping.h index 7a2ed154a5e1..e46bde61029b
>>> 100644 --- a/arch/x86/include/asm/irq_remapping.h
>>> +++ b/arch/x86/include/asm/irq_remapping.h
>>> @@ -50,6 +50,17 @@ static inline struct irq_domain
>>> *arch_get_ir_parent_domain(void) return x86_vector_domain;
>>> }
>>>
>>> +#ifdef CONFIG_X86_POSTED_MSI
>>> +extern int enable_posted_msi;
>>> +
>>> +static inline bool posted_msi_supported(void)
>>> +{
>>> + return enable_posted_msi && irq_remapping_cap(IRQ_POSTING_CAP);
>>> +}
>>
>> Out of this patch set's scope, but, dropping into irq_remappping_cap(),
>> I'd like to bring this change for discussion:
>>
>> diff --git a/drivers/iommu/irq_remapping.c b/drivers/iommu/irq_remapping.c
>> index 4047ac396728..ef2de9034897 100644
>> --- a/drivers/iommu/irq_remapping.c
>> +++ b/drivers/iommu/irq_remapping.c
>> @@ -98,7 +98,7 @@ void set_irq_remapping_broken(void)
>>
>> bool irq_remapping_cap(enum irq_remap_cap cap)
>> {
>> - if (!remap_ops || disable_irq_post)
>> + if (!remap_ops || disable_irq_remap)
>> return false;
>>
>> return (remap_ops->capability & (1 << cap));
>>
>>
>> 1. irq_remapping_cap() is to exam some cap, though at present it has only
>> 1 cap, i.e. IRQ_POSTING_CAP, simply return false just because of
>> disable_irq_post isn't good. Instead, IRQ_REMAP is the foundation of all
>> remapping caps. 2. disable_irq_post is used by Intel iommu code only,
>> here irq_remapping_cap() is common code. e.g. AMD iommu code doesn't use
>> it to judge set cap of irq_post or not.
> I agree, posting should be treated as a sub-capability of remapping.
> IRQ_POSTING_CAP is only set when remapping is on.
>
> We need to delete this such that posting is always off when remapping is
> off.
>
> --- a/drivers/iommu/intel/irq_remapping.c
> +++ b/drivers/iommu/intel/irq_remapping.c
> @@ -1038,11 +1038,7 @@ static void disable_irq_remapping(void)
> iommu_disable_irq_remapping(iommu);
> }
>
> - /*
> - * Clear Posted-Interrupts capability.
> - */
> - if (!disable_irq_post)
> - intel_irq_remap_ops.capability &= ~(1 << IRQ_POSTING_CAP);
> + intel_irq_remap_ops.capability &= ~(1 << IRQ_POSTING_CAP);
> }
>
Right.
Hi Kevin,
On Fri, 12 Apr 2024 09:31:32 +0000, "Tian, Kevin" <[email protected]>
wrote:
> > From: Jacob Pan <[email protected]>
> > Sent: Saturday, April 6, 2024 6:31 AM
> >
> > +#ifdef CONFIG_X86_POSTED_MSI
> > + else if (!strncmp(str, "posted_msi", 10)) {
> > + if (disable_irq_post || disable_irq_remap)
> > + pr_warn("Posted MSI not enabled due to
> > conflicting options!");
> > + else
> > + enable_posted_msi = 1;
> > + }
> > +#endif
>
> the check of disable_irq_remap is unnecessary. It's unlikely to have
> a configuration with disable_irq_post=0 while disable_irq_remap=1
> given the latter has bigger scope.
>
> but thinking more do we really need a check here? there is no order
> guarantee that "posted_msi" is parsed after the parameters deciding
> the value of two disable variables.
>
> it probably makes more sense to just set enable_posted_msi here
> and then do all required checks when picking up the irqchip in
> intel_irq_remapping_alloc().
Makes sense, I have a helper function posted_msi_supported() called in
intel_irq_remapping_alloc() already.
My intention was to alert negligent users, but is is not really necessary
as you said.
Thanks,
Jacob