Hi,
On 06/03/17 11:34, Eric Auger wrote:
> This patch flushes the device table entries into guest RAM.
> Both flat table and 2 stage tables are supported. DeviceId
> indexing is used.
>
> For each device listed in the device table, we also flush
> the translation table using the vgic_its_flush/restore_itt
> routines.
>
> On restore, devices are re-allocated and their itte are
> re-built.
Some minor things below.
In general I had quite some trouble to understand what's going on here,
though I convinced myself that this is correct. So could you add a bit
more comments here? For instance to explain that we have to explicitly
handle the L1 table on restore, but not on flush.
> Signed-off-by: Eric Auger <eric.auger@xxxxxxxxxx>
>
> ---
> v2 -> v3:
> - fix itt_addr bitmask in vgic_its_restore_dte
> - addition of return 0 in vgic_its_restore_ite moved to
> the ITE related patch
>
> v1 -> v2:
> - use 8 byte format for DTE and ITE
> - support 2 stage format
> - remove kvm parameter
> - ITT flush/restore moved in a separate patch
> - use deviceid indexing
> ---
> virt/kvm/arm/vgic/vgic-its.c | 144 ++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 142 insertions(+), 2 deletions(-)
>
> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
> index a216849..27ebabd 100644
> --- a/virt/kvm/arm/vgic/vgic-its.c
> +++ b/virt/kvm/arm/vgic/vgic-its.c
> @@ -1849,12 +1849,137 @@ static int vgic_its_restore_itt(struct vgic_its *its,
> }
>
> /**
> + * vgic_its_flush_dte - Flush a device table entry at a given GPA
> + *
> + * @its: ITS handle
> + * @dev: ITS device
> + * @ptr: GPA
> + */
> +static int vgic_its_flush_dte(struct vgic_its *its,
> + struct its_device *dev, gpa_t ptr)
> +{
> + struct kvm *kvm = its->dev->kvm;
> + u64 val, itt_addr_field;
> + int ret;
> + u32 next_offset;
> +
> + itt_addr_field = dev->itt_addr >> 8;
> + next_offset = compute_next_devid_offset(&its->device_list, dev);
> + val = (((u64)next_offset << 45) | (itt_addr_field << 5) |
So this gives you 19 bits for next_offset, but the value of
VITS_DTE_MAX_DEVID_OFFSET suggests 20 bits. It should become more
obvious what's happening here if use "BITS(x) - 1" at the definition as
suggested before.
Also you limit itt_addr here to 40 bits, where the actual limit seems to
be 44 bits (52 - 8). Is that limited by KVM somewhere else?
Even if it is, I think we should make sure that itt_addr_field doesn't
spill over into next_offset.
> + (dev->nb_eventid_bits - 1));
Mmmh, here nb_eventid_bits seems to be the real bit number again. Puzzled.
> + val = cpu_to_le64(val);
> + ret = kvm_write_guest(kvm, ptr, &val, 8);
> + return ret;
> +}
> +
> +/**
> + * vgic_its_restore_dte - restore a device table entry
> + *
> + * @its: its handle
> + * @id: device id the DTE corresponds to
> + * @ptr: kernel VA where the 8 byte DTE is located
> + * @opaque: unused
> + * @next: offset to the next valid device id
> + *
> + * Return: < 0 on error, 0 otherwise
> + */
> +static int vgic_its_restore_dte(struct vgic_its *its, u32 id,
> + void *ptr, void *opaque, u32 *next)
> +{
> + struct its_device *dev;
> + gpa_t itt_addr;
> + size_t size;
> + u64 val, *p = (u64 *)ptr;
> + int ret;
> +
> + val = *p;
> + val = le64_to_cpu(val);
> +
> + size = val & GENMASK_ULL(4, 0);
> + itt_addr = (val & GENMASK_ULL(44, 5)) >> 5;
> + *next = 1;
> +
> + if (!itt_addr)
> + return 0;
> +
> + /* dte entry is valid */
> + *next = (val & GENMASK_ULL(63, 45)) >> 45;
No need for GENMASK, just shift by 45.
> +
> + ret = vgic_its_alloc_device(its, &dev, id,
> + itt_addr, size);
> + if (ret)
> + return ret;
> + ret = vgic_its_restore_itt(its, dev);
> +
> + return ret;
> +}
> +
> +/**
> * vgic_its_flush_device_tables - flush the device table and all ITT
> * into guest RAM
> */
> static int vgic_its_flush_device_tables(struct vgic_its *its)
> {
> - return -ENXIO;
> + struct its_device *dev;
> + u64 baser;
> +
> + baser = its->baser_device_table;
> +
> + list_for_each_entry(dev, &its->device_list, dev_list) {
> + int ret;
> + gpa_t eaddr;
> +
> + if (!vgic_its_check_id(its, baser,
> + dev->device_id, &eaddr))
> + return -EINVAL;
> +
> + ret = vgic_its_flush_itt(its, dev);
> + if (ret)
> + return ret;
> +
> + ret = vgic_its_flush_dte(its, dev, eaddr);
> + if (ret)
> + return ret;
> + }
whitespace ?
> + return 0;
> +}
> +
> +/**
> + * handle_l1_entry - callback used for L1 entries (2 stage case)
> + *
> + * @its: its handle
> + * @id: id
> + * @addr: kernel VA
> + * @opaque: unused
> + * @next_offset: offset to the next L1 entry: 0 if the last element
> + * was found, 1 otherwise
> + */
> +static int handle_l1_entry(struct vgic_its *its, u32 id, void *addr,
> + void *opaque, u32 *next_offset)
> +{
> + u64 *pe = addr;
> + gpa_t gpa;
> + int l2_start_id = id * (SZ_64K / 8);
I think we can use GITS_LVL1_ENTRY_SIZE here, which I suppose is what
the 8 stands for.
> + int ret;
> +
> + *pe = le64_to_cpu(*pe);
Is it correct to _update_ the entry here? I think that breaks BE, right?
Beside I believe the ITS is not supposed to tinker with the L1 table
entries, isn't it?
So should it be instead:
u64 pe = *(u64 *)addr;
pe = le64_to_cpu(pe);
instead?
And what "pe" stand for anyway? Maybe "entry" instead?
> + *next_offset = 1;
> +
> + if (!(*pe & BIT_ULL(63)))
> + return 0;
> +
> + gpa = *pe & GENMASK_ULL(51, 16);
> +
> + ret = lookup_table(its, gpa, SZ_64K, 8,
> + l2_start_id, vgic_its_restore_dte, NULL);
> +
> + if (ret == 1) {
> + /* last entry was found in this L2 table */
> + *next_offset = 0;
> + ret = 0;
> + }
> +
> + return ret;
> }
>
> /**
> @@ -1863,7 +1988,22 @@ static int vgic_its_flush_device_tables(struct vgic_its *its)
> */
> static int vgic_its_restore_device_tables(struct vgic_its *its)
> {
> - return -ENXIO;
> + u64 baser = its->baser_device_table;
> + int l1_tbl_size = GITS_BASER_NR_PAGES(baser) * SZ_64K;
> + int l1_esz = GITS_BASER_ENTRY_SIZE(baser);
> + gpa_t l1_gpa;
> +
> + l1_gpa = BASER_ADDRESS(baser);
> + if (!l1_gpa)
> + return 0;
> +
> + if (!(baser & GITS_BASER_INDIRECT))
> + return lookup_table(its, l1_gpa, l1_tbl_size, l1_esz,
> + 0, vgic_its_restore_dte, NULL);
> +
> + /* two stage table */
> + return lookup_table(its, l1_gpa, l1_tbl_size, 8, 0,
> + handle_l1_entry, NULL);
That usage of lookup_table with the callback is pretty neat!
Cheers,
Andre.
> }
>
> static int vgic_its_flush_cte(struct vgic_its *its,
>
