diff options
| author | Jacob Pan <jacob.jun.pan@linux.intel.com> | 2024-04-23 20:41:10 +0300 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2024-04-30 01:54:42 +0300 |
| commit | 1b03d82ba15e895776f1f7da2bb56a9a60e6dfed (patch) | |
| tree | 7a666ce9fe4221b79d8a8ec06400ad4ebc04618a /arch/x86/include | |
| parent | 6087c7f36ab293a06bc0bcf3857ed4d7eb1f9905 (diff) | |
| download | linux-1b03d82ba15e895776f1f7da2bb56a9a60e6dfed.tar.xz | |
x86/irq: Install posted MSI notification handler
All MSI vectors are multiplexed into a single notification vector when
posted MSI is enabled. It is the responsibility of the notification vector
handler to demultiplex MSI vectors. In the handler the MSI vector handlers
are dispatched without IDT delivery for each pending MSI interrupt.
For example, the interrupt flow will change as follows:
(3 MSIs of different vectors arrive in a a high frequency burst)
BEFORE:
interrupt(MSI)
irq_enter()
handler() /* EOI */
irq_exit()
process_softirq()
interrupt(MSI)
irq_enter()
handler() /* EOI */
irq_exit()
process_softirq()
interrupt(MSI)
irq_enter()
handler() /* EOI */
irq_exit()
process_softirq()
AFTER:
interrupt /* Posted MSI notification vector */
irq_enter()
atomic_xchg(PIR)
handler()
handler()
handler()
pi_clear_on()
apic_eoi()
irq_exit()
process_softirq()
Except for the leading MSI, CPU notifications are skipped/coalesced.
For MSIs which arrive at a low frequency, the demultiplexing loop does not
wait for more interrupts to coalesce. Therefore, there's no additional
latency other than the processing time.
Signed-off-by: Jacob Pan <jacob.jun.pan@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240423174114.526704-9-jacob.jun.pan@linux.intel.com
Diffstat (limited to 'arch/x86/include')
| -rw-r--r-- | arch/x86/include/asm/hardirq.h | 3 | ||||
| -rw-r--r-- | arch/x86/include/asm/idtentry.h | 6 |
2 files changed, 9 insertions, 0 deletions
diff --git a/arch/x86/include/asm/hardirq.h b/arch/x86/include/asm/hardirq.h index e7ab594b3a7a..c67fa6ad098a 100644 --- a/arch/x86/include/asm/hardirq.h +++ b/arch/x86/include/asm/hardirq.h @@ -44,6 +44,9 @@ typedef struct { unsigned int irq_hv_reenlightenment_count; unsigned int hyperv_stimer0_count; #endif +#ifdef CONFIG_X86_POSTED_MSI + unsigned int posted_msi_notification_count; +#endif } ____cacheline_aligned irq_cpustat_t; DECLARE_PER_CPU_SHARED_ALIGNED(irq_cpustat_t, irq_stat); diff --git a/arch/x86/include/asm/idtentry.h b/arch/x86/include/asm/idtentry.h index 749c7411d2f1..d4f24499b256 100644 --- a/arch/x86/include/asm/idtentry.h +++ b/arch/x86/include/asm/idtentry.h @@ -751,6 +751,12 @@ DECLARE_IDTENTRY_SYSVEC(POSTED_INTR_NESTED_VECTOR, sysvec_kvm_posted_intr_nested # define fred_sysvec_kvm_posted_intr_nested_ipi NULL #endif +# ifdef CONFIG_X86_POSTED_MSI +DECLARE_IDTENTRY_SYSVEC(POSTED_MSI_NOTIFICATION_VECTOR, sysvec_posted_msi_notification); +#else +# define fred_sysvec_posted_msi_notification NULL +# endif + #if IS_ENABLED(CONFIG_HYPERV) DECLARE_IDTENTRY_SYSVEC(HYPERVISOR_CALLBACK_VECTOR, sysvec_hyperv_callback); DECLARE_IDTENTRY_SYSVEC(HYPERV_REENLIGHTENMENT_VECTOR, sysvec_hyperv_reenlightenment); |