Re: [PATCH v10 09/17] KVM: arm64: introduce ITS emulation file with MMIO framework

Andre Przywara
2016-07-18T16:34:32Z

Hi Eric,

On 18/07/16 10:18, Auger Eric wrote:
> Hi Andre, Marc,
>
> On 15/07/2016 13:43, Andre Przywara wrote:
>> The ARM GICv3 ITS emulation code goes into a separate file, but needs
>> to be connected to the GICv3 emulation, of which it is an option.
>> The ITS MMIO handlers require the respective ITS pointer to be passed in,
>> so we amend the existing VGIC MMIO framework to let it cope with that.
>> Also we introduce the basic ITS data structure and initialize it, but
>> don't return any success yet, as we are not yet ready for the show.
>>
>> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
>> ---
>> include/kvm/arm_vgic.h | 22 ++++++++-
>> virt/kvm/arm/vgic/vgic-its.c | 103 +++++++++++++++++++++++++++++++++++++++
>> virt/kvm/arm/vgic/vgic-mmio-v3.c | 40 ++++++++++++++-
>> virt/kvm/arm/vgic/vgic-mmio.c | 37 +++++++++++---
>> virt/kvm/arm/vgic/vgic-mmio.h | 17 +++++--
>> virt/kvm/arm/vgic/vgic.h | 7 +++
>> 6 files changed, 213 insertions(+), 13 deletions(-)
>> create mode 100644 virt/kvm/arm/vgic/vgic-its.c
>>
>> diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
>> index df2dec5..685f339 100644
>> --- a/include/kvm/arm_vgic.h
>> +++ b/include/kvm/arm_vgic.h
>> @@ -108,15 +108,35 @@ struct vgic_irq {
>> };
>>
>> struct vgic_register_region;
>> +struct vgic_its;
>> +
>> +enum iodev_type {
>> + IODEV_CPUIF,
>> + IODEV_DIST,
>> + IODEV_REDIST,
>> + IODEV_ITS
>> +};
>>
>> struct vgic_io_device {
>> gpa_t base_addr;
>> - struct kvm_vcpu *redist_vcpu;
>> + union {
>> + struct kvm_vcpu *redist_vcpu;
>> + struct vgic_its *its;
>> + };
>> const struct vgic_register_region *regions;
>> + enum iodev_type iodev_type;
>> int nr_regions;
>> struct kvm_io_device dev;
>> };
>>
>> +struct vgic_its {
>> + /* The base address of the ITS control register frame */
>> + gpa_t vgic_its_base;
>> +
>> + bool enabled;
>> + struct vgic_io_device iodev;
>> +};
>> +
>> struct vgic_dist {
>> bool in_kernel;
>> bool ready;
>> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
>> new file mode 100644
>> index 0000000..4654d6e
>> --- /dev/null
>> +++ b/virt/kvm/arm/vgic/vgic-its.c
>> @@ -0,0 +1,103 @@
>> +/*
>> + * GICv3 ITS emulation
>> + *
>> + * Copyright (C) 2015,2016 ARM Ltd.
>> + * Author: Andre Przywara <andre.przywara@arm.com>
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License version 2 as
>> + * published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
>> + * GNU General Public License for more details.
>> + *
>> + * You should have received a copy of the GNU General Public License
>> + * along with this program. If not, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#include <linux/cpu.h>
>> +#include <linux/kvm.h>
>> +#include <linux/kvm_host.h>
>> +#include <linux/interrupt.h>
>> +
>> +#include <linux/irqchip/arm-gic-v3.h>
>> +
>> +#include <asm/kvm_emulate.h>
>> +#include <asm/kvm_arm.h>
>> +#include <asm/kvm_mmu.h>
>> +
>> +#include "vgic.h"
>> +#include "vgic-mmio.h"
>> +
>> +#define REGISTER_ITS_DESC(off, rd, wr, length, acc) \
>> +{ \
>> + .reg_offset = off, \
>> + .len = length, \
>> + .access_flags = acc, \
>> + .its_read = rd, \
>> + .its_write = wr, \
>> +}
>> +
>> +static unsigned long its_mmio_read_raz(struct kvm *kvm, struct vgic_its *its,
>> + gpa_t addr, unsigned int len)
>> +{
>> + return 0;
>> +}
>> +
>> +static void its_mmio_write_wi(struct kvm *kvm, struct vgic_its *its,
>> + gpa_t addr, unsigned int len, unsigned long val)
>> +{
>> + /* Ignore */
>> +}
>> +
>> +static struct vgic_register_region its_registers[] = {
>> + REGISTER_ITS_DESC(GITS_CTLR,
>> + its_mmio_read_raz, its_mmio_write_wi, 4,
>> + VGIC_ACCESS_32bit),
>> + REGISTER_ITS_DESC(GITS_IIDR,
>> + its_mmio_read_raz, its_mmio_write_wi, 4,
>> + VGIC_ACCESS_32bit),
>> + REGISTER_ITS_DESC(GITS_TYPER,
>> + its_mmio_read_raz, its_mmio_write_wi, 8,
>> + VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
>> + REGISTER_ITS_DESC(GITS_CBASER,
>> + its_mmio_read_raz, its_mmio_write_wi, 8,
>> + VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
>> + REGISTER_ITS_DESC(GITS_CWRITER,
>> + its_mmio_read_raz, its_mmio_write_wi, 8,
>> + VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
>> + REGISTER_ITS_DESC(GITS_CREADR,
>> + its_mmio_read_raz, its_mmio_write_wi, 8,
>> + VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
>> + REGISTER_ITS_DESC(GITS_BASER,
>> + its_mmio_read_raz, its_mmio_write_wi, 0x40,
>> + VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
>> + REGISTER_ITS_DESC(GITS_IDREGS_BASE,
>> + its_mmio_read_raz, its_mmio_write_wi, 0x30,
>> + VGIC_ACCESS_32bit),
>> +};
>> +
>> +static int vgic_its_init_its(struct kvm *kvm, struct vgic_its *its)
>> +{
>> + struct vgic_io_device *iodev = &its->iodev;
>> + int ret;
>> +
>> + if (IS_VGIC_ADDR_UNDEF(its->vgic_its_base))
>> + return -ENXIO;
>> +
>> + iodev->regions = its_registers;
>> + iodev->nr_regions = ARRAY_SIZE(its_registers);
>> + kvm_iodevice_init(&iodev->dev, &kvm_io_gic_ops);
>> +
>> + iodev->base_addr = its->vgic_its_base;
>> + iodev->iodev_type = IODEV_ITS;
>> + iodev->its = its;
>> + mutex_lock(&kvm->slots_lock);
>> + ret = kvm_io_bus_register_dev(kvm, KVM_MMIO_BUS, iodev->base_addr,
>> + KVM_VGIC_V3_ITS_SIZE, &iodev->dev);
>> + mutex_unlock(&kvm->slots_lock);
>> +
>> + return ret;
>> +}
>> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v3.c b/virt/kvm/arm/vgic/vgic-mmio-v3.c
>> index 278bfbb..b92b7d6 100644
>> --- a/virt/kvm/arm/vgic/vgic-mmio-v3.c
>> +++ b/virt/kvm/arm/vgic/vgic-mmio-v3.c
>> @@ -42,6 +42,16 @@ static u64 update_64bit_reg(u64 reg, unsigned int offset, unsigned int len,
>> return reg | ((u64)val << lower);
>> }
>>
>> +bool vgic_has_its(struct kvm *kvm)
>> +{
>> + struct vgic_dist *dist = &kvm->arch.vgic;
>> +
>> + if (dist->vgic_model != KVM_DEV_TYPE_ARM_VGIC_V3)
>> + return false;
>> +
>> + return false;
>> +}
>> +
>> static unsigned long vgic_mmio_read_v3_misc(struct kvm_vcpu *vcpu,
>> gpa_t addr, unsigned int len)
>> {
>> @@ -132,6 +142,32 @@ static void vgic_mmio_write_irouter(struct kvm_vcpu *vcpu,
>> vgic_put_irq(vcpu->kvm, irq);
>> }
>>
>> +static unsigned long vgic_mmio_read_v3r_ctlr(struct kvm_vcpu *vcpu,
>> + gpa_t addr, unsigned int len)
>> +{
>> + struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
>> +
>> + return vgic_cpu->lpis_enabled ? GICR_CTLR_ENABLE_LPIS : 0;
>> +}
>> +
>> +
>> +static void vgic_mmio_write_v3r_ctlr(struct kvm_vcpu *vcpu,
>> + gpa_t addr, unsigned int len,
>> + unsigned long val)
>> +{
>> + struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
>> + bool was_enabled = vgic_cpu->lpis_enabled;
>> +
>> + if (!vgic_has_its(vcpu->kvm))
>> + return;
>> +
>> + vgic_cpu->lpis_enabled = val & GICR_CTLR_ENABLE_LPIS;
>> +
>> + if (!was_enabled && vgic_cpu->lpis_enabled) {
>> + /* Eventually do something */
>> + }
>> +}
>> +
>> static unsigned long vgic_mmio_read_v3r_typer(struct kvm_vcpu *vcpu,
>> gpa_t addr, unsigned int len)
>> {
>> @@ -372,7 +408,7 @@ static const struct vgic_register_region vgic_v3_dist_registers[] = {
>>
>> static const struct vgic_register_region vgic_v3_rdbase_registers[] = {
>> REGISTER_DESC_WITH_LENGTH(GICR_CTLR,
>> - vgic_mmio_read_raz, vgic_mmio_write_wi, 4,
>> + vgic_mmio_read_v3r_ctlr, vgic_mmio_write_v3r_ctlr, 4,
>> VGIC_ACCESS_32bit),
>> REGISTER_DESC_WITH_LENGTH(GICR_IIDR,
>> vgic_mmio_read_v3r_iidr, vgic_mmio_write_wi, 4,
>> @@ -450,6 +486,7 @@ int vgic_register_redist_iodevs(struct kvm *kvm, gpa_t redist_base_address)
>>
>> kvm_iodevice_init(&rd_dev->dev, &kvm_io_gic_ops);
>> rd_dev->base_addr = rd_base;
>> + rd_dev->iodev_type = IODEV_REDIST;
>> rd_dev->regions = vgic_v3_rdbase_registers;
>> rd_dev->nr_regions = ARRAY_SIZE(vgic_v3_rdbase_registers);
>> rd_dev->redist_vcpu = vcpu;
>> @@ -464,6 +501,7 @@ int vgic_register_redist_iodevs(struct kvm *kvm, gpa_t redist_base_address)
>>
>> kvm_iodevice_init(&sgi_dev->dev, &kvm_io_gic_ops);
>> sgi_dev->base_addr = sgi_base;
>> + sgi_dev->iodev_type = IODEV_REDIST;
>> sgi_dev->regions = vgic_v3_sgibase_registers;
>> sgi_dev->nr_regions = ARRAY_SIZE(vgic_v3_sgibase_registers);
>> sgi_dev->redist_vcpu = vcpu;
>> diff --git a/virt/kvm/arm/vgic/vgic-mmio.c b/virt/kvm/arm/vgic/vgic-mmio.c
>> index 5e79e01..26be827 100644
>> --- a/virt/kvm/arm/vgic/vgic-mmio.c
>> +++ b/virt/kvm/arm/vgic/vgic-mmio.c
>> @@ -473,8 +473,7 @@ static int dispatch_mmio_read(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
>> {
>> struct vgic_io_device *iodev = kvm_to_vgic_iodev(dev);
>> const struct vgic_register_region *region;
>> - struct kvm_vcpu *r_vcpu;
>> - unsigned long data;
>> + unsigned long data = 0;
>>
>> region = vgic_find_mmio_region(iodev->regions, iodev->nr_regions,
>> addr - iodev->base_addr);
>> @@ -483,8 +482,20 @@ static int dispatch_mmio_read(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
>> return 0;
>> }
>>
>> - r_vcpu = iodev->redist_vcpu ? iodev->redist_vcpu : vcpu;
>> - data = region->read(r_vcpu, addr, len);
>> + switch (iodev->iodev_type) {
>> + case IODEV_CPUIF:
>> + return 1;
> This change causes a regression on AMD Seattle with QEMU (abort with
> message "restoring 288 IRQs, but kernel supports max 32").
> Shoudn't we have
> data = region->read(vcpu, addr, len);
> break;
> This path is exercised by vgic_v2_cpuif_uaccess/vgic_uaccess

Of course! At the time I was writing this it totally slipped me that the
new VGIC _is_ using this code path now for the save/restore, so we need
to handle that here.

Apologies for the mess, and thanks a ton Eric for spotting this (and for
the fix)!
(for the records: kvmtool does not save/restore registers, so this code
never gets triggered there).

Cheers,
Andre.

>> + case IODEV_DIST:
>> + data = region->read(vcpu, addr, len);
>> + break;
>> + case IODEV_REDIST:
>> + data = region->read(iodev->redist_vcpu, addr, len);
>> + break;
>> + case IODEV_ITS:
>> + data = region->its_read(vcpu->kvm, iodev->its, addr, len);
>> + break;
>> + }
>> +
>> vgic_data_host_to_mmio_bus(val, len, data);
>> return 0;
>> }
>> @@ -494,7 +505,6 @@ static int dispatch_mmio_write(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
>> {
>> struct vgic_io_device *iodev = kvm_to_vgic_iodev(dev);
>> const struct vgic_register_region *region;
>> - struct kvm_vcpu *r_vcpu;
>> unsigned long data = vgic_data_mmio_bus_to_host(val, len);
>>
>> region = vgic_find_mmio_region(iodev->regions, iodev->nr_regions,
>> @@ -505,8 +515,20 @@ static int dispatch_mmio_write(struct kvm_vcpu *vcpu, struct kvm_io_device *dev,
>> if (!check_region(region, addr, len))
>> return 0;
>>
>> - r_vcpu = iodev->redist_vcpu ? iodev->redist_vcpu : vcpu;
>> - region->write(r_vcpu, addr, len, data);
>> + switch (iodev->iodev_type) {
>> + case IODEV_CPUIF:
>> + break;
> same here
> region->write(vcpu, addr, len, data);
>
> The above modifications fix the issue.
>
> Eric
>> + case IODEV_DIST:
>> + region->write(vcpu, addr, len, data);
>> + break;
>> + case IODEV_REDIST:
>> + region->write(iodev->redist_vcpu, addr, len, data);
>> + break;
>> + case IODEV_ITS:
>> + region->its_write(vcpu->kvm, iodev->its, addr, len, data);
>> + break;
>> + }
>> +
>> return 0;
>> }
>>
>> @@ -536,6 +558,7 @@ int vgic_register_dist_iodev(struct kvm *kvm, gpa_t dist_base_address,
>> }
>>
>> io_device->base_addr = dist_base_address;
>> + io_device->iodev_type = IODEV_DIST;
>> io_device->redist_vcpu = NULL;
>>
>> mutex_lock(&kvm->slots_lock);
>> diff --git a/virt/kvm/arm/vgic/vgic-mmio.h b/virt/kvm/arm/vgic/vgic-mmio.h
>> index 71aa39d..366d663 100644
>> --- a/virt/kvm/arm/vgic/vgic-mmio.h
>> +++ b/virt/kvm/arm/vgic/vgic-mmio.h
>> @@ -21,10 +21,19 @@ struct vgic_register_region {
>> unsigned int len;
>> unsigned int bits_per_irq;
>> unsigned int access_flags;
>> - unsigned long (*read)(struct kvm_vcpu *vcpu, gpa_t addr,
>> - unsigned int len);
>> - void (*write)(struct kvm_vcpu *vcpu, gpa_t addr, unsigned int len,
>> - unsigned long val);
>> + union {
>> + unsigned long (*read)(struct kvm_vcpu *vcpu, gpa_t addr,
>> + unsigned int len);
>> + unsigned long (*its_read)(struct kvm *kvm, struct vgic_its *its,
>> + gpa_t addr, unsigned int len);
>> + };
>> + union {
>> + void (*write)(struct kvm_vcpu *vcpu, gpa_t addr,
>> + unsigned int len, unsigned long val);
>> + void (*its_write)(struct kvm *kvm, struct vgic_its *its,
>> + gpa_t addr, unsigned int len,
>> + unsigned long val);
>> + };
>> };
>>
>> extern struct kvm_io_device_ops kvm_io_gic_ops;
>> diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
>> index 5b79c34..31807c1 100644
>> --- a/virt/kvm/arm/vgic/vgic.h
>> +++ b/virt/kvm/arm/vgic/vgic.h
>> @@ -72,6 +72,7 @@ void vgic_v3_enable(struct kvm_vcpu *vcpu);
>> int vgic_v3_probe(const struct gic_kvm_info *info);
>> int vgic_v3_map_resources(struct kvm *kvm);
>> int vgic_register_redist_iodevs(struct kvm *kvm, gpa_t dist_base_address);
>> +bool vgic_has_its(struct kvm *kvm);
>> #else
>> static inline void vgic_v3_process_maintenance(struct kvm_vcpu *vcpu)
>> {
>> @@ -123,6 +124,12 @@ static inline int vgic_register_redist_iodevs(struct kvm *kvm,
>> {
>> return -ENODEV;
>> }
>> +
>> +static inline bool vgic_has_its(struct kvm *kvm)
>> +{
>> + return false;
>> +}
>> +
>> #endif
>>
>> int kvm_register_vgic_device(unsigned long type);
>>
>