irqchip/gic-v3-its: Use allocation size from the prepare call

Now that .msi_prepare() gets called at the right time and not
with semi-random parameters, remove the ugly hack that tried
to fix up the number of allocated vectors.

It is now correct by construction.

Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250513163144.2215824-6-maz@kernel.org

Author: Marc Zyngier

drivers/irqchip/irq-gic-v3-its-msi-parent.c

@@ -67,17 +67,6 @@ static int its_pci_msi_prepare(struct irq_domain *domain, struct device *dev,
 	/* ITS specific DeviceID, as the core ITS ignores dev. */
 	info->scratchpad[0].ul = pci_msi_domain_get_msi_rid(domain->parent, pdev);
 
-	/*
-	 * @domain->msi_domain_info->hwsize contains the size of the
-	 * MSI[-X] domain, but vector allocation happens one by one. This
-	 * needs some thought when MSI comes into play as the size of MSI
-	 * might be unknown at domain creation time and therefore set to
-	 * MSI_MAX_INDEX.
-	 */
-	msi_info = msi_get_domain_info(domain);
-	if (msi_info->hwsize > nvec)
-		nvec = msi_info->hwsize;
-
 	/*
 	 * Always allocate a power of 2, and special case device 0 for
 	 * broken systems where the DevID is not wired (and all devices
@@ -151,14 +140,6 @@ static int its_pmsi_prepare(struct irq_domain *domain, struct device *dev,
 	/* ITS specific DeviceID, as the core ITS ignores dev. */
 	info->scratchpad[0].ul = dev_id;
 
-	/*
-	 * @domain->msi_domain_info->hwsize contains the size of the device
-	 * domain, but vector allocation happens one by one.
-	 */
-	msi_info = msi_get_domain_info(domain);
-	if (msi_info->hwsize > nvec)
-		nvec = msi_info->hwsize;
-
 	/* Allocate at least 32 MSIs, and always as a power of 2 */
 	nvec = max_t(int, 32, roundup_pow_of_two(nvec));