On 18/08/12 04:00, Christoffer Dall wrote:
> On Thu, Jul 5, 2012 at 11:28 AM, Marc Zyngier <marc.zyngier@xxxxxxx> wrote:
>> Wire the initial in-kernel MMIO support code for the VGIC, used
>> for the distributor emulation.
>>
>> Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
>> ---
>> arch/arm/include/asm/kvm_vgic.h | 5 +-
>> arch/arm/kvm/Makefile | 1 +
>> arch/arm/kvm/mmu.c | 25 +++++---
>> arch/arm/kvm/vgic.c | 127 +++++++++++++++++++++++++++++++++++++++
>> 4 files changed, 150 insertions(+), 8 deletions(-)
>> create mode 100644 arch/arm/kvm/vgic.c
>>
>> diff --git a/arch/arm/include/asm/kvm_vgic.h b/arch/arm/include/asm/kvm_vgic.h
>> index 8e8bd6d..59c2f60 100644
>> --- a/arch/arm/include/asm/kvm_vgic.h
>> +++ b/arch/arm/include/asm/kvm_vgic.h
>> @@ -12,7 +12,10 @@ struct kvm_vcpu;
>> struct kvm_run;
>> struct kvm_exit_mmio;
>>
>> -#ifndef CONFIG_KVM_ARM_VGIC
>> +#ifdef CONFIG_KVM_ARM_VGIC
>> +int vgic_handle_mmio(struct kvm_vcpu *vcpu, struct kvm_run *run,
>> + struct kvm_exit_mmio *mmio);
>> +#else
>> static inline int kvm_vgic_hyp_init(void)
>> {
>> return 0;
>> diff --git a/arch/arm/kvm/Makefile b/arch/arm/kvm/Makefile
>> index 5f40c5a..c5c4a9f 100644
>> --- a/arch/arm/kvm/Makefile
>> +++ b/arch/arm/kvm/Makefile
>> @@ -15,3 +15,4 @@ kvm-arm-y += $(addprefix ../../../virt/kvm/, kvm_main.o coalesced_mmio.o)
>> kvm-arm-y += arm.o guest.o mmu.o emulate.o reset.o
>>
>> obj-$(CONFIG_KVM) += kvm-arm.o
>> +obj-$(CONFIG_KVM_ARM_VGIC) += vgic.o
>> diff --git a/arch/arm/kvm/mmu.c b/arch/arm/kvm/mmu.c
>> index 4955a51..d63e05e 100644
>> --- a/arch/arm/kvm/mmu.c
>> +++ b/arch/arm/kvm/mmu.c
>> @@ -641,10 +641,16 @@ static int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
>> /* Get instruction length in bytes */
>> instr_len = (vcpu->arch.hsr & HSR_IL) ? 4 : 2;
>>
>> - /* Export MMIO operations to user space */
>> - run->mmio.is_write = is_write;
>> - run->mmio.phys_addr = fault_ipa;
>> - run->mmio.len = len;
>> + /*
>> + * Prepare MMIO operation. First stash it in a private
>> + * structure that we can use for in-kernel emulation. If the
>> + * kernel can not handle it, copy it into run->mmio (as it is
>> + * garanteed to be the same type) and let user space do its
>> + * magic.
>> + */
>> + mmio.mmio.is_write = is_write;
>> + mmio.mmio.phys_addr = fault_ipa;
>> + mmio.mmio.len = len;
>> vcpu->arch.mmio_sign_extend = sign_extend;
>> vcpu->arch.mmio_rd = rd;
>>
>> @@ -653,9 +659,14 @@ static int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
>> len, fault_ipa, (is_write) ? *vcpu_reg(vcpu, rd) : 0);
>>
>> if (is_write)
>> - memcpy(run->mmio.data, vcpu_reg(vcpu, rd), len);
>> + memcpy(mmio.mmio.data, vcpu_reg(vcpu, rd), len);
>>
>> - run->exit_reason = vgic_handle_mmio(vcpu, run);
>> + run->exit_reason = vgic_handle_mmio(vcpu, run, &mmio);
>> + switch (run->exit_reason) {
>> + case KVM_EXIT_MMIO:
>> + run->mmio = mmio.mmio;
>> + break;
>> + }
>
> Is this switch going to expand or is it really an "if
> (run->exit_reason == KVM_EXIT_MMIO)" ?
The switch is gone in recent versions on this patch.
> or, if memory serves me right, it's rather the opposite case, perhaps
> even turn vgic_handle_mmio into a bool and do:
>
> kvm_skip_instr(...);
>
> if (vgic_handle_mmio(vcpu, run &mmio))
> return 1;
I suppose kvm_skip_instr() is a recent addition. In which case, this
would work.
> /* Emulate in user space */
> run->mmio.XXX = mmio.XXX;
> run->mmio.YYY = mmio.YYY;
> run->exit_reason = KVM_EXIT_MMIO;
> return 0;
>
>
> I think we should just define the mmio structure with whatever we
> need, and then set the fields, field by field, if we need to copy to
> vcpu->run, then avoid the weird type coherent construction that might
> leave people pondering for hours why the need for the fancyness. Or
> maybe that's just me?
Whatever we need is exactly all the fields in the mmio structure. I'm
trying to ensure consistency between userspace and in-kernel emulation.
If you feel this is superfluous, I'll get rid of it.
>
>>
>> /*
>> * The MMIO instruction is emulated and should not be re-executed
>> @@ -664,7 +675,7 @@ static int io_mem_abort(struct kvm_vcpu *vcpu, struct kvm_run *run,
>> *vcpu_pc(vcpu) += instr_len;
>> kvm_adjust_itstate(vcpu);
>> vcpu->stat.mmio_exits++;
>> - return KVM_EXIT_MMIO;
>> + return run->exit_reason;
>
> see above, but in any case this needs to be adjusted when rebased onto
> kvm-a15-v10 (yes, I know it's my fault keeping this around for so
> long)
This has already been changed for v10/v11.
>> }
>>
>> /**
>> diff --git a/arch/arm/kvm/vgic.c b/arch/arm/kvm/vgic.c
>> new file mode 100644
>> index 0000000..0502212
>> --- /dev/null
>> +++ b/arch/arm/kvm/vgic.c
>> @@ -0,0 +1,127 @@
>> +/*
>> + * Copyright (C) 2012 ARM Ltd.
>> + * Author: Marc Zyngier <marc.zyngier@xxxxxxx>
>> + *
>> + * 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, write to the Free Software
>> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
>> + */
>> +
>> +#include <linux/kvm.h>
>> +#include <linux/kvm_host.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/io.h>
>> +#include <asm/kvm_emulate.h>
>> +
>> +#define ACCESS_READ_VALUE (1 << 0)
>> +#define ACCESS_READ_RAZ (0 << 0)
>> +#define ACCESS_READ_MASK(x) ((x) & (1 << 0))
>> +#define ACCESS_WRITE_IGNORED (0 << 1)
>> +#define ACCESS_WRITE_SETBIT (1 << 1)
>> +#define ACCESS_WRITE_CLEARBIT (2 << 1)
>> +#define ACCESS_WRITE_VALUE (3 << 1)
>> +#define ACCESS_WRITE_MASK(x) ((x) & (3 << 1))
>> +
>
> sorry, it might be me who's just damp, but this would really help me
> next time I have to read it:
>
> /**
> * vgic_reg_access - access vgic register
> * @mmio: pointer to the data describing the mmio access
> * @reg: pointer to the virtual backing of the vgic distributor struct
> * @offset: least significant 2 bits used for word offset
> * @mode: ACCESS_ mode (see defines above)
> *
> * Helper to make vgic register access easier using one of the access modes
> * defined for vgic register access
> (read,raz,write-ignored,setbit,clearbit,write)
> */
>
>> +static void vgic_reg_access(struct kvm_exit_mmio *mmio, u32 *reg, u32 offset, int mode)
>> +{
>> + int word_offset = offset & 3;
>> + int shift = word_offset * 8;
>> + u32 mask;
>> + u32 regval;
>> +
>> + /*
>> + * Any alignment fault should have been delivered to the guest
>> + * directly (ARM ARM B3.12.7 "Prioritization of aborts").
>> + */
>> +
>> + mask = (~0U) >> (word_offset * 8);
>> + if (reg)
>> + regval = *reg;
>> + else {
>> + BUG_ON(mode != (ACCESS_READ_RAZ | ACCESS_WRITE_IGNORED));
>> + regval = 0;
>> + }
>> +
>> + if (mmio->mmio.is_write) {
>> + u32 data = (*((u32 *)mmio->mmio.data) & mask) << shift;
>> + switch (ACCESS_WRITE_MASK(mode)) {
>> + case ACCESS_WRITE_IGNORED:
>> + return;
>> +
>> + case ACCESS_WRITE_SETBIT:
>> + regval |= data;
>> + break;
>> +
>> + case ACCESS_WRITE_CLEARBIT:
>> + regval &= ~data;
>> + break;
>> +
>> + case ACCESS_WRITE_VALUE:
>> + regval = (regval & ~(mask << shift)) | data;
>> + break;
>> + }
>> + *reg = regval;
>> + } else {
>> + switch (ACCESS_READ_MASK(mode)) {
>> + case ACCESS_READ_RAZ:
>> + regval = 0;
>> + /* fall through */
>> +
>> + case ACCESS_READ_VALUE:
>> + *((u32 *)mmio->mmio.data) = (regval >> shift) & mask;
>> + }
>> + }
>> +}
>> +
>> +/* All this should be handled by kvm_bus_io_*()... FIXME!!! */
>> +struct mmio_range {
>> + unsigned long base;
>> + unsigned long len;
>> + void (*handle_mmio)(struct kvm_vcpu *vcpu, struct kvm_exit_mmio *mmio,
>> + u32 offset);
>> +};
>> +
>> +static const struct mmio_range vgic_ranges[] = {
>> + {}
>> +};
>> +
>> +static const
>> +struct mmio_range *find_matching_range(const struct mmio_range *ranges,
>> + struct kvm_exit_mmio *mmio,
>> + unsigned long base)
>> +{
>> + const struct mmio_range *r = ranges;
>> + unsigned long addr = mmio->mmio.phys_addr - base;
>> +
>> + while (r->len) {
>> + if (addr >= r->base &&
>> + (addr + mmio->mmio.len) <= (r->base + r->len))
>> + return r;
>> + r++;
>> + }
>> +
>> + return NULL;
>> +}
>> +
>> +/**
>> + * vgic_handle_mmio - handle an in-kernel MMIO access
>> + * @vcpu: pointer to the vcpu performing the access
>> + * @mmio: pointer to the data describing the access
>> + *
>> + * returns KVM_EXIT_UNKNOWN if the MMIO access has been performed
>> + * in kernel space, and KVM_EXIT_MMIO if it needs to be emulated
>> + * in user space.
>
> as per previous comment, could be just "return true if MMIO access has
> been handled here"
>
>> + */
>> +int vgic_handle_mmio(struct kvm_vcpu *vcpu, struct kvm_run *run, struct kvm_exit_mmio *mmio)
>> +{
>> + return KVM_EXIT_MMIO;
>> +}
>> --
>> 1.7.10.3
>>
>>
>
> besides the cosmetic comments, looks good to me.
>
--
Jazz is not dead. It just smells funny...
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