Re: [PATCH v4 14/18] KVM: arm64: selftests: Add host support for vGIC

[Andrew Jones]

On Thu, Sep 09, 2021 at 05:32:43AM +0000, Oliver Upton wrote:
> Hi Raghu,
> 
> On Thu, Sep 09, 2021 at 01:38:14AM +0000, Raghavendra Rao Ananta wrote:
> > Implement a simple library to perform vGIC-v3 setup
> > from a host point of view. This includes creating a
> > vGIC device, setting up distributor and redistributor
> > attributes, and mapping the guest physical addresses.
> > 
> > The definition of REDIST_REGION_ATTR_ADDR is taken
> > from aarch64/vgic_init test.
> >
> 
> Consider dropping the macro from vgic_init.c and have it just include
> vgic.h

Yes, I agree 18/18 should be squashed into this one.

> 
> > Signed-off-by: Raghavendra Rao Ananta <rananta@xxxxxxxxxx>
> > ---
> >  tools/testing/selftests/kvm/Makefile          |  2 +-
> >  .../selftests/kvm/include/aarch64/vgic.h      | 20 +++++++
> >  .../testing/selftests/kvm/lib/aarch64/vgic.c  | 60 +++++++++++++++++++
> >  3 files changed, 81 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..3a776af958a0
> > --- /dev/null
> > +++ b/tools/testing/selftests/kvm/include/aarch64/vgic.h
> > @@ -0,0 +1,20 @@
> > +/* 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>
> > +
> > +#define REDIST_REGION_ATTR_ADDR(count, base, flags, index) \
> > +	(((uint64_t)(count) << 52) | \
> > +	((uint64_t)((base) >> 16) << 16) | \
> > +	((uint64_t)(flags) << 12) | \
> > +	index)
> > +
> > +int vgic_v3_setup(struct kvm_vm *vm,
> > +				uint64_t gicd_base_gpa, uint64_t gicr_base_gpa);
> > +
> > +#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..2318912ab134
> > --- /dev/null
> > +++ b/tools/testing/selftests/kvm/lib/aarch64/vgic.c
> > @@ -0,0 +1,60 @@
> > +// 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"
> > +#include "vgic.h"
> > +
> > +#define VGIC_V3_GICD_SZ		(SZ_64K)
> > +#define VGIC_V3_GICR_SZ		(2 * SZ_64K)
> 
> These values are UAPI, consider dropping them in favor of the
> definitions from asm/kvm.h

Yes, please.

> 
> > +
> > +/*
> > + * vGIC-v3 default host setup
> > + *
> > + * Input args:
> > + *	vm - KVM 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. Since it depends on the number of
> > + * vCPUs for the VM, it must be called after all the vCPUs have been created.
> 
> You could avoid the ordering dependency by explicitly taking nr_vcpus as
> an arg. It would also avoid the need for 12/18.

All the vcpus need to be created prior to calling
KVM_DEV_ARM_VGIC_CTRL_INIT, so even though I don't disagree with
simply passing nr_vcpus to this function, we should still assert
if the VM's idea of the number doesn't match. But, this is a lib
file, so there's no reason not to do

#include "../kvm_util_internal.h"

and just access the vcpu list to get the count or, if we add a
new internal nr_vcpus member, access it directly. IOW, so far
I don't believe we need vm_get_nr_vcpus().

> 
> Also note the required alignment on the GPA arguments you're taking.
> 
> > + */
> > +int vgic_v3_setup(struct kvm_vm *vm,
> > +		uint64_t gicd_base_gpa, uint64_t gicr_base_gpa)
> > +{
> > +	uint64_t redist_attr;
> > +	int gic_fd, nr_vcpus;
> > +	unsigned int nr_gic_pages;
> > +
> > +	nr_vcpus = vm_get_nr_vcpus(vm);
> > +	TEST_ASSERT(nr_vcpus > 0, "Invalid number of CPUs: %u\n", nr_vcpus);
> > +
> > +	/* Distributor setup */
> > +	gic_fd = kvm_create_device(vm, KVM_DEV_TYPE_ARM_VGIC_V3, false);
> > +	kvm_device_access(gic_fd, KVM_DEV_ARM_VGIC_GRP_ADDR,
> > +			KVM_VGIC_V3_ADDR_TYPE_DIST, &gicd_base_gpa, true);
> > +	nr_gic_pages = vm_calc_num_guest_pages(vm_get_mode(vm), VGIC_V3_GICD_SZ);
> > +	virt_map(vm, gicd_base_gpa, gicd_base_gpa,  nr_gic_pages);
> > +
> > +	/* Redistributor setup */
> > +	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);
> > +	nr_gic_pages = vm_calc_num_guest_pages(vm_get_mode(vm),
> > +						VGIC_V3_GICR_SZ * nr_vcpus);
> > +	virt_map(vm, gicr_base_gpa, gicr_base_gpa,  nr_gic_pages);
> > +
> > +	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
> > 
>

Thanks,
drew