[PATCH 3/3] irqchip/riscv-imsic: Remove global nr_guest_files after KVM AIA per-HART conversion

[guoren at kernel.org]

From: "Guo Ren (Alibaba DAMO Academy)" <guoren at kernel.org>

With the recent KVM AIA changes, HGEI line management is now fully
per-CPU (via struct aia_hgei_control::nr_hgei) and the global
kvm_riscv_aia_nr_hgei has been replaced by a simple enabled flag.
The IMSIC driver no longer needs to compute and enforce a global
minimum number of guest interrupt files across all HARTs.

Remove:
 - `u32 nr_guest_files` from `struct imsic_global_config`
 - the initial `BIT(global->guest_index_bits) - 1` assignment
 - the entire per-CPU MMIO-based min() calculation and its comment
   (which was specifically there to protect old KVM)

The per-HART guest file count is already handled locally in
`imsic_local_config` during the parent IRQ loop, so this global
field was redundant.

This completes the cleanup series, eliminates the last global
assumption about guest files, and improves support for heterogeneous
(big.LITTLE / multi-vendor) RISC-V platforms.

Signed-off-by: Guo Ren (Alibaba DAMO Academy) <guoren at kernel.org>
---
 drivers/irqchip/irq-riscv-imsic-state.c | 12 +-----------
 include/linux/irqchip/riscv-imsic.h     |  3 ---
 2 files changed, 1 insertion(+), 14 deletions(-)

diff --git a/drivers/irqchip/irq-riscv-imsic-state.c b/drivers/irqchip/irq-riscv-imsic-state.c
index e3ed874d89e7..fef27247a34f 100644
--- a/drivers/irqchip/irq-riscv-imsic-state.c
+++ b/drivers/irqchip/irq-riscv-imsic-state.c
@@ -784,7 +784,7 @@ static int __init imsic_parse_fwnode(struct fwnode_handle *fwnode,
 
 int __init imsic_setup_state(struct fwnode_handle *fwnode, void *opaque)
 {
-	u32 i, j, index, nr_parent_irqs, nr_mmios, nr_guest_files, nr_handlers = 0;
+	u32 i, j, index, nr_parent_irqs, nr_mmios, nr_handlers = 0;
 	struct imsic_global_config *global;
 	struct imsic_local_config *local;
 	void __iomem **mmios_va = NULL;
@@ -878,7 +878,6 @@ int __init imsic_setup_state(struct fwnode_handle *fwnode, void *opaque)
 	}
 
 	/* Configure handlers for target CPUs */
-	global->nr_guest_files = BIT(global->guest_index_bits) - 1;
 	for (i = 0; i < nr_parent_irqs; i++) {
 		rc = imsic_get_parent_hartid(fwnode, i, &hartid);
 		if (rc) {
@@ -919,15 +918,6 @@ int __init imsic_setup_state(struct fwnode_handle *fwnode, void *opaque)
 		local->msi_pa = mmios[index].start + reloff;
 		local->msi_va = mmios_va[index] + reloff;
 
-		/*
-		 * KVM uses global->nr_guest_files to determine the available guest
-		 * interrupt files on each CPU. Take the minimum number of guest
-		 * interrupt files across all CPUs to avoid KVM incorrectly allocating
-		 * an unexisted or unmapped guest interrupt file on some CPUs.
-		 */
-		nr_guest_files = (resource_size(&mmios[index]) - reloff) / IMSIC_MMIO_PAGE_SZ - 1;
-		global->nr_guest_files = min(global->nr_guest_files, nr_guest_files);
-
 		nr_handlers++;
 	}
 
diff --git a/include/linux/irqchip/riscv-imsic.h b/include/linux/irqchip/riscv-imsic.h
index 4b348836de7a..7f3ff5c5ea53 100644
--- a/include/linux/irqchip/riscv-imsic.h
+++ b/include/linux/irqchip/riscv-imsic.h
@@ -68,9 +68,6 @@ struct imsic_global_config {
 	/* Number of guest interrupt identities */
 	u32					nr_guest_ids;
 
-	/* Number of guest interrupt files per core */
-	u32					nr_guest_files;
-
 	/* Per-CPU IMSIC addresses */
 	struct imsic_local_config __percpu	*local;
 };
-- 
2.40.1