[tip: x86/irq] iommu/vt-d: Make posted MSI an opt-in command line option

tip-bot2 for Jacob Pan
2024-04-30T13:28:42Z

The following commit has been merged into the x86/irq branch of tip:

Commit-ID: be9be07b22c96dc03d0ecc76b5a5f21c2dcb05a1
Gitweb: https://git.kernel.org/tip/be9be07b22c96dc03d0ecc76b5a5f21c2dcb05a1
Author: Jacob Pan <jacob.jun.pan@linux.intel.com>
AuthorDate: Tue, 23 Apr 2024 10:41:13 -07:00
Committer: Thomas Gleixner <tglx@linutronix.de>
CommitterDate: Tue, 30 Apr 2024 00:54:43 +02:00

iommu/vt-d: Make posted MSI an opt-in command line option

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@linux.intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/r/20240423174114.526704-12-jacob.jun.pan@linux.intel.com

---
Documentation/admin-guide/kernel-parameters.txt | 2 ++
arch/x86/include/asm/irq_remapping.h | 7 +++++++
drivers/iommu/irq_remapping.c | 5 ++++-
3 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 902ecd9..dfbe9fd 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -2251,6 +2251,8 @@
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 7a2ed15..5036f13 100644
--- a/arch/x86/include/asm/irq_remapping.h
+++ b/arch/x86/include/asm/irq_remapping.h
@@ -50,6 +50,13 @@ static inline struct irq_domain *arch_get_ir_parent_domain(void)
return x86_vector_domain;
}

+extern bool enable_posted_msi;
+
+static inline bool posted_msi_supported(void)
+{
+ return enable_posted_msi && irq_remapping_cap(IRQ_POSTING_CAP);
+}
+
#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 ee59647..056fec6 100644
--- a/drivers/iommu/irq_remapping.c
+++ b/drivers/iommu/irq_remapping.c
@@ -24,6 +24,8 @@ int no_x2apic_optout;

int disable_irq_post = 0;

+bool enable_posted_msi __ro_after_init;
+
static int disable_irq_remap;
static struct irq_remap_ops *remap_ops;

@@ -70,7 +72,8 @@ static __init int setup_irqremap(char *str)
no_x2apic_optout = 1;
else if (!strncmp(str, "nopost", 6))
disable_irq_post = 1;
-
+ else if (IS_ENABLED(CONFIG_X86_POSTED_MSI) && !strncmp(str, "posted_msi", 10))
+ enable_posted_msi = true;
str += strcspn(str, ",");
while (*str == ',')
str++;