[PATCH v6 10/24] KVM: arm64: vgic-its: Implement vgic_mmio_uaccess_write_its_iidr

[Marc Zyngier]

On 04/05/17 12:44, Eric Auger wrote:
> The GITS_IIDR revision field is used to encode the migration ABI
> revision. So we need to restore it to check the table layout is
> readable by the destination.
> 
> By writing the IIDR, userspace thus forces the ABI revision to be
> used and this must be less than or equal to the max revision KVM
> supports.
> 
> Signed-off-by: Eric Auger <eric.auger at redhat.com>
> 
> ---
> v5 -> v6:
> - fix typos in the commit message
> - dont't use update_64bit_reg anymore
> 
> v4 -> v5
> - rename user_revision into abi_rev and REV into MAX_ABI_REV
> - IIDR reports abi_rev set by userspace if any.
> - If value set by userspace exceeds the max supported revision, an
>   error is reported.
> - add some defines
> 
> v4: creation
> ---
>  include/linux/irqchip/arm-gic-v3.h |  4 ++++
>  virt/kvm/arm/vgic/vgic-its.c       | 20 +++++++++++++++++---
>  2 files changed, 21 insertions(+), 3 deletions(-)
> 
> diff --git a/include/linux/irqchip/arm-gic-v3.h b/include/linux/irqchip/arm-gic-v3.h
> index 81ebe43..59f1abd 100644
> --- a/include/linux/irqchip/arm-gic-v3.h
> +++ b/include/linux/irqchip/arm-gic-v3.h
> @@ -242,6 +242,10 @@
>  #define GITS_TYPER_PTA			(1UL << 19)
>  #define GITS_TYPER_HWCOLLCNT_SHIFT	24
>  
> +#define GITS_IIDR_REV_SHIFT		12
> +#define GITS_IIDR_REV(r)		(((r) >> GITS_IIDR_REV_SHIFT) & 0xf)
> +#define GITS_IIDR_PRODUCTID_SHIFT	24
> +
>  #define GITS_CBASER_VALID			(1ULL << 63)
>  #define GITS_CBASER_SHAREABILITY_SHIFT		(10)
>  #define GITS_CBASER_INNER_CACHEABILITY_SHIFT	(59)
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index c336cce..072efbd 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -411,7 +411,20 @@ static unsigned long vgic_mmio_read_its_iidr(struct kvm *kvm,
>  					     struct vgic_its *its,
>  					     gpa_t addr, unsigned int len)
>  {
> -	return (PRODUCT_ID_KVM << 24) | (IMPLEMENTER_ARM << 0);
> +	return (PRODUCT_ID_KVM << GITS_IIDR_PRODUCTID_SHIFT) |
> +	       (its->abi_rev << GITS_IIDR_REV_SHIFT) | IMPLEMENTER_ARM;

Given that abi_rev is a 32bit quantity, and the REV field only only 4
bit wide, I'd feel safer with a mask somewhere...

And hopefully, we'll never have more than 16 ABIs! ;-)

> +}
> +
> +static int vgic_mmio_uaccess_write_its_iidr(struct kvm *kvm,
> +					    struct vgic_its *its,
> +					    gpa_t addr, unsigned int len,
> +					    unsigned long val)
> +{
> +	u32 rev = GITS_IIDR_REV(val);
> +
> +	if (rev > MAX_ABI_REV)
> +		return -EINVAL;
> +	return vgic_its_set_abi(its, rev);
>  }
>  
>  static unsigned long vgic_mmio_read_its_idregs(struct kvm *kvm,
> @@ -1393,8 +1406,9 @@ static struct vgic_register_region its_registers[] = {
>  	REGISTER_ITS_DESC(GITS_CTLR,
>  		vgic_mmio_read_its_ctlr, vgic_mmio_write_its_ctlr, 4,
>  		VGIC_ACCESS_32bit),
> -	REGISTER_ITS_DESC(GITS_IIDR,
> -		vgic_mmio_read_its_iidr, its_mmio_write_wi, 4,
> +	REGISTER_ITS_DESC_UACCESS(GITS_IIDR,
> +		vgic_mmio_read_its_iidr, its_mmio_write_wi,
> +		vgic_mmio_uaccess_write_its_iidr, 4,
>  		VGIC_ACCESS_32bit),
>  	REGISTER_ITS_DESC(GITS_TYPER,
>  		vgic_mmio_read_its_typer, its_mmio_write_wi, 8,
> 

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...