Hi Robert,
On Sat, 6 Apr 2024 12:31:14 +0800, Robert Hoo <robert.hoo.linux@xxxxxxxxx>
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 <jacob.jun.pan@xxxxxxxxxxxxxxx>
> > ---
> > 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
