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)" ?
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;
/* 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?
>
> /*
> * 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)
> }
>
> /**
> 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.
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