Re: [PATCH v5 12/22] KVM: arm64: vgic-its: Interpret MAPD ITT_addr field

Christoffer Dall
2017-04-27T18:09:11Z

On Thu, Apr 27, 2017 at 07:44:25PM +0200, Auger Eric wrote:
> Hi,
>
> On 27/04/2017 18:43, Christoffer Dall wrote:
> > On Fri, Apr 14, 2017 at 12:15:24PM +0200, Eric Auger wrote:
> >> Up to now the MAPD ITT_addr had been ignored. We will need it
> >> for save/restore. Let's record it in the its_device struct.
> >>
> >> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> >>
> >> ---
> >> v4 -> v5:
> >> - its_cmd_get_ittaddr macro now returns the actual ITT GPA
> >>
> >> v3 -> v4:
> >> - in vgic_its_cmd_handle_mapd, itt_addr directly is shifted
> >> - correct ittaddr bitmask to support 48bit GPA
> >> ---
> >> virt/kvm/arm/vgic/vgic-its.c | 4 ++++
> >> 1 file changed, 4 insertions(+)
> >>
> >> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> >> index 0f3c8f3..757598d 100644
> >> --- a/virt/kvm/arm/vgic/vgic-its.c
> >> +++ b/virt/kvm/arm/vgic/vgic-its.c
> >> @@ -106,6 +106,7 @@ struct its_device {
> >> /* the head for the list of ITTEs */
> >> struct list_head itt_head;
> >> u32 nb_eventid_bits;
> >> + gpa_t itt_addr;
> >> u32 device_id;
> >> };
> >>
> >> @@ -569,6 +570,7 @@ static u64 its_cmd_mask_field(u64 *its_cmd, int word, int shift, int size)
> >> #define its_cmd_get_id(cmd) its_cmd_mask_field(cmd, 1, 0, 32)
> >> #define its_cmd_get_physical_id(cmd) its_cmd_mask_field(cmd, 1, 32, 32)
> >> #define its_cmd_get_collection(cmd) its_cmd_mask_field(cmd, 2, 0, 16)
> >> +#define its_cmd_get_ittaddr(cmd) (its_cmd_mask_field(cmd, 2, 8, 47) << 8)
> >
> > Why 47? The ITT_addr field is bits [51:8] unless I'm looking at
> > something wrong?
>
> Initially I limited to 48 bits since I found in the code:
>
> /*
> * We only implement 48 bits of PA at the moment, although the ITS
> * supports more. Let's be restrictive here.
> */
> #define BASER_ADDRESS(x) ((x) & GENMASK_ULL(47, 16))
> #define CBASER_ADDRESS(x) ((x) & GENMASK_ULL(47, 12))
>
> But practically as I encode the ITT addr field on 52 bits now in the DTE
> there is no reason anymore.

Well, regardless, shouldn't you be bassing 44 to its_cmd_mask_field(),
because you're shifting left 8 bits afterwards?

Thanks,
-Christoffer