Subject: Re: [PATCH v3 10/12] KVM: arm64: selftests: Add host support for vGIC

From: Ricardo Koller <[email-masked]>
Date: Thu, 2 Sep 2021 10:28:23 -0700

On Wed, Sep 01, 2021 at 09:14:10PM +0000, Raghavendra Rao Ananta wrote:
> Implement a simple library to do perform vGIC-v3
> setup from a host of view. This includes creating
> a vGIC device, setting up distributor and redistributor
> attributes, and mapping the guest physical addresses.
> 
> Signed-off-by: Raghavendra Rao Ananta <[email-masked]>
> 
> ---
>  tools/testing/selftests/kvm/Makefile          |  2 +-
>  .../selftests/kvm/include/aarch64/vgic.h      | 14 ++++
>  .../testing/selftests/kvm/lib/aarch64/vgic.c  | 67 +++++++++++++++++++
>  3 files changed, 82 insertions(+), 1 deletion(-)
>  create mode 100644 tools/testing/selftests/kvm/include/aarch64/vgic.h
>  create mode 100644 tools/testing/selftests/kvm/lib/aarch64/vgic.c
> 
> diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
> index 5476a8ddef60..8342f65c1d96 100644
> --- a/tools/testing/selftests/kvm/Makefile
> +++ b/tools/testing/selftests/kvm/Makefile
> @@ -35,7 +35,7 @@ endif
>  
>  LIBKVM = lib/assert.c lib/elf.c lib/io.c lib/kvm_util.c lib/rbtree.c lib/sparsebit.c lib/test_util.c lib/guest_modes.c lib/perf_test_util.c
>  LIBKVM_x86_64 = lib/x86_64/apic.c lib/x86_64/processor.c lib/x86_64/vmx.c lib/x86_64/svm.c lib/x86_64/ucall.c lib/x86_64/handlers.S
> -LIBKVM_aarch64 = lib/aarch64/processor.c lib/aarch64/ucall.c lib/aarch64/handlers.S lib/aarch64/spinlock.c lib/aarch64/gic.c lib/aarch64/gic_v3.c
> +LIBKVM_aarch64 = lib/aarch64/processor.c lib/aarch64/ucall.c lib/aarch64/handlers.S lib/aarch64/spinlock.c lib/aarch64/gic.c lib/aarch64/gic_v3.c lib/aarch64/vgic.c
>  LIBKVM_s390x = lib/s390x/processor.c lib/s390x/ucall.c lib/s390x/diag318_test_handler.c
>  
>  TEST_GEN_PROGS_x86_64 = x86_64/cr4_cpuid_sync_test
> diff --git a/tools/testing/selftests/kvm/include/aarch64/vgic.h b/tools/testing/selftests/kvm/include/aarch64/vgic.h
> new file mode 100644
> index 000000000000..45bbf238147a
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/include/aarch64/vgic.h
> @@ -0,0 +1,14 @@
> +/* SPDX-License-Identifier: GPL-2.0 */
> +/*
> + * ARM Generic Interrupt Controller (GIC) host specific defines
> + */
> +
> +#ifndef SELFTEST_KVM_VGIC_H
> +#define SELFTEST_KVM_VGIC_H
> +
> +#include <linux/kvm.h>
> +
> +int vgic_v3_setup(struct kvm_vm *vm, unsigned int nr_vcpus,
> +		uint64_t gicd_base_gpa, uint64_t gicr_base_gpa, uint32_t slot);
> +
> +#endif /* SELFTEST_KVM_VGIC_H */
> diff --git a/tools/testing/selftests/kvm/lib/aarch64/vgic.c b/tools/testing/selftests/kvm/lib/aarch64/vgic.c
> new file mode 100644
> index 000000000000..a0e4b986d335
> --- /dev/null
> +++ b/tools/testing/selftests/kvm/lib/aarch64/vgic.c
> @@ -0,0 +1,67 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * ARM Generic Interrupt Controller (GIC) v3 host support
> + */
> +
> +#include <linux/kvm.h>
> +#include <linux/sizes.h>
> +
> +#include "kvm_util.h"
> +
> +#define VGIC_V3_GICD_SZ		(SZ_64K)
> +#define VGIC_V3_GICR_SZ		(2 * SZ_64K)
> +
> +#define REDIST_REGION_ATTR_ADDR(count, base, flags, index) \
> +	(((uint64_t)(count) << 52) | \
> +	((uint64_t)((base) >> 16) << 16) | \
> +	((uint64_t)(flags) << 12) | \
> +	index)
> +
> +static void vgic_v3_map(struct kvm_vm *vm, uint64_t addr, unsigned int size)
> +{
> +	unsigned int n_pages = DIV_ROUND_UP(size, vm_get_page_size(vm));
> +
> +	virt_map(vm, addr, addr, n_pages);
> +}
> +
> +/*
> + * vGIC-v3 default host setup
> + *
> + * Input args:
> + *	vm - KVM VM
> + *	nr_vcpus - Number of vCPUs for this VM
> + *	gicd_base_gpa - Guest Physical Address of the Distributor region
> + *	gicr_base_gpa - Guest Physical Address of the Redistributor region
> + *
> + * Output args: None
> + *
> + * Return: GIC file-descriptor or negative error code upon failure
> + *
> + * The function creates a vGIC-v3 device and maps the distributor and
> + * redistributor regions of the guest.
> + */
> +int vgic_v3_setup(struct kvm_vm *vm, unsigned int nr_vcpus,
> +		uint64_t gicd_base_gpa, uint64_t gicr_base_gpa)
> +{
> +	uint64_t redist_attr;
> +	int gic_fd;
> +
> +	TEST_ASSERT(nr_vcpus <= KVM_MAX_VCPUS,
> +			"Invalid number of CPUs: %u\n", nr_vcpus);
> +
> +	gic_fd = kvm_create_device(vm, KVM_DEV_TYPE_ARM_VGIC_V3, false);

Nit: you can return early if gic_fd is bad.

> +
> +	kvm_device_access(gic_fd, KVM_DEV_ARM_VGIC_GRP_ADDR,
> +			KVM_VGIC_V3_ADDR_TYPE_DIST, &gicd_base_gpa, true);
> +	vgic_v3_map(vm, gicd_base_gpa, VGIC_V3_GICD_SZ);

vgic_v3_map() implies that it's doing something vgic specific, when it's
just converting bytes to pages. What about something like the following?

	virt_map(vm, addr, addr, VM_BYTES_TO_PAGES(vm, VGIC_V3_GICD_SZ));

and you add a VM_BYTES_TO_PAGES macro to include/kvm_util.h? I think
this macro can be useful to others.

> +
> +	redist_attr = REDIST_REGION_ATTR_ADDR(nr_vcpus, gicr_base_gpa, 0, 0);
> +	kvm_device_access(gic_fd, KVM_DEV_ARM_VGIC_GRP_ADDR,
> +			KVM_VGIC_V3_ADDR_TYPE_REDIST_REGION, &redist_attr, true);
> +	vgic_v3_map(vm, gicr_base_gpa, VGIC_V3_GICR_SZ * nr_vcpus);
> +
> +	kvm_device_access(gic_fd, KVM_DEV_ARM_VGIC_GRP_CTRL,
> +				KVM_DEV_ARM_VGIC_CTRL_INIT, NULL, true);
> +
> +	return gic_fd;
> +}
> -- 
> 2.33.0.153.gba50c8fa24-goog
> 

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