[PATCH v2 5/5] KVM: arm64: selftests: Test VGICv3 redistributor region retry

[Karl Mehltretter <kmehltretter@gmail.com>]

A failed REDIST_REGION write can remove redistributor iodevs without
clearing their cached vCPU assignments. A retry then skips those
assignments and leaves the redistributors absent from the MMIO bus.

Create two partial regions, reject a third region that overlaps the
distributor, and retry at a valid address. After initializing the VGIC,
have the guest read GICR_TYPER from all four redistributors and check their
processor numbers. This verifies the final configuration without assuming
that assignments survive the failed write.

Keep the redistributor IPAs outside the guest RAM memslot and install only
the stage-1 mappings needed for the MMIO accesses. If an iodev is missing,
KVM_RUN therefore exits with KVM_EXIT_MMIO. Without the fix, the first
redistributor access exits at 0x8030008.

Assisted-by: Codex:gpt-5.6-sol
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
---
 tools/testing/selftests/kvm/arm64/vgic_init.c | 91 +++++++++++++++++++
 1 file changed, 91 insertions(+)

diff --git a/tools/testing/selftests/kvm/arm64/vgic_init.c b/tools/testing/selftests/kvm/arm64/vgic_init.c
index 91484fd4f786..6d9998c764bc 100644
--- a/tools/testing/selftests/kvm/arm64/vgic_init.c
+++ b/tools/testing/selftests/kvm/arm64/vgic_init.c
@@ -5,6 +5,7 @@
  * Copyright (C) 2020, Red Hat, Inc.
  */
 #include <linux/kernel.h>
+#include <linux/sizes.h>
 #include <sys/syscall.h>
 #include <asm/kvm.h>
 #include <asm/kvm_para.h>
@@ -13,12 +14,21 @@
 
 #include "test_util.h"
 #include "kvm_util.h"
+#include "gic.h"
 #include "processor.h"
 #include "vgic.h"
 #include "gic_v3.h"
 
 #define NR_VCPUS		4
 
+#define REDIST_RETRY_REGION0_BASE	GICR_BASE_GPA
+#define REDIST_RETRY_REGION1_BASE	\
+	(REDIST_RETRY_REGION0_BASE + 2 * KVM_VGIC_V3_REDIST_SIZE)
+#define REDIST_RETRY_DIST_BASE		\
+	(REDIST_RETRY_REGION1_BASE + KVM_VGIC_V3_REDIST_SIZE)
+#define REDIST_RETRY_REGION2_BASE	\
+	(REDIST_RETRY_DIST_BASE + KVM_VGIC_V3_DIST_SIZE)
+
 #define REG_OFFSET(vcpu, offset) (((u64)vcpu << 32) | offset)
 
 #define VGIC_DEV_IS_V2(_d) ((_d) == KVM_DEV_TYPE_ARM_VGIC_V2)
@@ -65,6 +75,22 @@ static void guest_code(void)
 	GUEST_DONE();
 }
 
+static void guest_check_redist_retry(void)
+{
+	unsigned int i;
+
+	for (i = 0; i < NR_VCPUS; i++) {
+		u64 base = i < 3 ? REDIST_RETRY_REGION0_BASE +
+				       i * KVM_VGIC_V3_REDIST_SIZE :
+				       REDIST_RETRY_REGION2_BASE;
+		u64 typer = readq((void *)(unsigned long)(base + GICR_TYPER));
+
+		GUEST_ASSERT_EQ(GICR_TYPER_CPU_NUMBER(typer), i);
+	}
+
+	GUEST_DONE();
+}
+
 /* we don't want to assert on run execution, hence that helper */
 static int run_vcpu(struct kvm_vcpu *vcpu)
 {
@@ -462,6 +488,70 @@ static void test_v3_new_redist_regions(void)
 	vm_gic_destroy(&v);
 }
 
+static void test_v3_redist_region_retry(void)
+{
+	struct kvm_vcpu *vcpus[NR_VCPUS];
+	struct vm_gic v;
+	struct ucall uc;
+	u64 addr;
+	int ret;
+
+	v = vm_gic_create_with_vcpus(KVM_DEV_TYPE_ARM_VGIC_V3, NR_VCPUS,
+				     guest_check_redist_retry, vcpus);
+
+	addr = REDIST_REGION_ATTR_ADDR(2, REDIST_RETRY_REGION0_BASE, 0, 0);
+	kvm_device_attr_set(v.gic_fd, KVM_DEV_ARM_VGIC_GRP_ADDR,
+			    KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION, &addr);
+
+	addr = REDIST_REGION_ATTR_ADDR(1, REDIST_RETRY_REGION1_BASE, 0, 1);
+	kvm_device_attr_set(v.gic_fd, KVM_DEV_ARM_VGIC_GRP_ADDR,
+			    KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION, &addr);
+
+	addr = REDIST_RETRY_DIST_BASE;
+	kvm_device_attr_set(v.gic_fd, KVM_DEV_ARM_VGIC_GRP_ADDR,
+			    KVM_VGIC_V3_ADDR_TYPE_DIST, &addr);
+
+	addr = REDIST_REGION_ATTR_ADDR(1, REDIST_RETRY_DIST_BASE, 0, 2);
+	ret = __kvm_device_attr_set(v.gic_fd, KVM_DEV_ARM_VGIC_GRP_ADDR,
+				    KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION,
+				    &addr);
+	TEST_ASSERT(ret && errno == EINVAL,
+		    "register redist region colliding with dist");
+
+	addr = REDIST_REGION_ATTR_ADDR(1, REDIST_RETRY_REGION2_BASE, 0, 2);
+	kvm_device_attr_set(v.gic_fd, KVM_DEV_ARM_VGIC_GRP_ADDR,
+			    KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION, &addr);
+
+	virt_map(v.vm, REDIST_RETRY_REGION0_BASE, REDIST_RETRY_REGION0_BASE,
+		 vm_calc_num_guest_pages(v.vm->mode,
+					 3 * KVM_VGIC_V3_REDIST_SIZE));
+	virt_map(v.vm, REDIST_RETRY_REGION2_BASE, REDIST_RETRY_REGION2_BASE,
+		 vm_calc_num_guest_pages(v.vm->mode,
+					 KVM_VGIC_V3_REDIST_SIZE));
+
+	kvm_device_attr_set(v.gic_fd, KVM_DEV_ARM_VGIC_GRP_CTRL,
+			    KVM_DEV_ARM_VGIC_CTRL_INIT, NULL);
+
+	vcpu_run(vcpus[0]);
+	switch (get_ucall(vcpus[0], &uc)) {
+	case UCALL_DONE:
+		break;
+	case UCALL_ABORT:
+		REPORT_GUEST_ASSERT(uc);
+		break;
+	case UCALL_NONE:
+		if (vcpus[0]->run->exit_reason == KVM_EXIT_MMIO)
+			TEST_FAIL("Unexpected MMIO exit at 0x%llx",
+				  vcpus[0]->run->mmio.phys_addr);
+		fallthrough;
+	default:
+		TEST_FAIL("Unexpected ucall %lu, exit_reason %u",
+			  uc.cmd, vcpus[0]->run->exit_reason);
+	}
+
+	vm_gic_destroy(&v);
+}
+
 static void test_v3_typer_accesses(void)
 {
 	struct vm_gic v;
@@ -986,6 +1076,7 @@ void run_tests(u32 gic_dev_type)
 
 	if (VGIC_DEV_IS_V3(gic_dev_type)) {
 		test_v3_new_redist_regions();
+		test_v3_redist_region_retry();
 		test_v3_typer_accesses();
 		test_v3_last_bit_redist_regions();
 		test_v3_last_bit_single_rdist();
-- 
2.39.5 (Apple Git-154)