On 14/07/18 18:05, Christoffer Dall wrote:
> Currently we do not allow any vgic mmio write operations to fail, which
> makes sense from mmio traps from the guest. However, we should be able
> to report failures to userspace, if userspace writes incompatible values
> to read-only registers. Rework the internal interface to allow errors
> to be returned on the write side for userspace writes.
>
> Signed-off-by: Christoffer Dall <christoffer.dall@xxxxxxx>
> ---
> virt/kvm/arm/vgic/vgic-mmio-v2.c | 26 +++++++++++++++++++++-----
> virt/kvm/arm/vgic/vgic-mmio-v3.c | 31 ++++++++++++++++++++++++-------
> virt/kvm/arm/vgic/vgic-mmio.c | 18 +++++++++++++-----
> virt/kvm/arm/vgic/vgic-mmio.h | 19 +++++++++++--------
> 4 files changed, 69 insertions(+), 25 deletions(-)
>
> diff --git a/virt/kvm/arm/vgic/vgic-mmio-v2.c b/virt/kvm/arm/vgic/vgic-mmio-v2.c
> index 34e36fc..b79de42 100644
> --- a/virt/kvm/arm/vgic/vgic-mmio-v2.c
> +++ b/virt/kvm/arm/vgic/vgic-mmio-v2.c
> @@ -77,11 +77,26 @@ static void vgic_mmio_write_v2_misc(struct kvm_vcpu *vcpu,
> }
> }
>
> -static void vgic_mmio_uaccess_write_v2_group(struct kvm_vcpu *vcpu,
> - gpa_t addr, unsigned int len,
> - unsigned long val)
> +static int vgic_mmio_uaccess_write_v2_misc(struct kvm_vcpu *vcpu,
> + gpa_t addr, unsigned int len,
> + unsigned long val)
> +{
> + switch (addr & 0x0c) {
> + case GIC_DIST_IIDR:
> + if (val != vgic_mmio_read_v2_misc(vcpu, addr, len))
> + return -EINVAL;
> + }
> +
> + vgic_mmio_write_v2_misc(vcpu, addr, len, val);
> + return 0;
> +}
> +
> +static int vgic_mmio_uaccess_write_v2_group(struct kvm_vcpu *vcpu,
> + gpa_t addr, unsigned int len,
> + unsigned long val)
> {
> /* Ignore writes from userspace */
> + return 0;
> }
I think it'd make more sense if this patch came before the previous one
(change the prototype of the userspace accessor, and only then add a new
accessor that can return an error). It would avoid churn in the above
function, and you could move vgic_mmio_uaccess_write_v2_misc into patch 6.
Not a big deal though, as the code is otherwise perfectly fine.
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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