Re: [PATCH v5 08/22] KVM: arm64: vgic-its: Implement vgic_mmio_uaccess_write_its_creadr

Auger Eric
2017-04-27T12:53:14Z

Hi,

On 27/04/2017 13:27, Christoffer Dall wrote:
> On Fri, Apr 14, 2017 at 12:15:20PM +0200, Eric Auger wrote:
>> GITS_CREADR needs to be restored so let's implement the associated
>> uaccess_write_its callback. The write only is allowed if the its
>> is disabled.
>>
>> Signed-off-by: Eric Auger <eric.auger@redhat.com>
>>
>> ---
>> v4 -> v5:
>> - keep Stalled bit
>> - vgic_mmio_uaccess_write_its_creadr can now return an error
>>
>> v3 -> v4:
>> - REGISTER_ITS_DESC_UACCESS now introduced in this patch
>> - we now check the its is disabled
>> ---
>> virt/kvm/arm/vgic/vgic-its.c | 42 ++++++++++++++++++++++++++++++++++++++++--
>> 1 file changed, 40 insertions(+), 2 deletions(-)
>>
>> diff --git a/virt/kvm/arm/vgic/vgic-its.c b/virt/kvm/arm/vgic/vgic-its.c
>> index a9a2c12..79ed1c2 100644
>> --- a/virt/kvm/arm/vgic/vgic-its.c
>> +++ b/virt/kvm/arm/vgic/vgic-its.c
>> @@ -1213,6 +1213,33 @@ static unsigned long vgic_mmio_read_its_creadr(struct kvm *kvm,
>> return extract_bytes(its->creadr, addr & 0x7, len);
>> }
>>
>> +static int vgic_mmio_uaccess_write_its_creadr(struct kvm *kvm,
>> + struct vgic_its *its,
>> + gpa_t addr, unsigned int len,
>> + unsigned long val)
>> +{
>> + int ret = 0;
>> + u32 reg;
>> +
>> + mutex_lock(&its->cmd_lock);
>> +
>> + if (its->enabled) {
>> + ret = -EBUSY;
>> + goto out;
>> + }
>> +
>> + reg = update_64bit_reg(its->creadr, addr & 7, len, val);
>
> you theoretically don't need this, since you prevent 32-bit accesses to
> this register, but I guess it doesn't hurt...
OK
>
>> + if (ITS_CMD_OFFSET(reg) >= ITS_CMD_BUFFER_SIZE(its->cbaser)) {
>> + ret = -EINVAL;
>> + goto out;
>> + }
>
> can the creadr value be unaligned to the command size? I don't think
> you check that anywhere here?
makes sense. I will add this check.

Thanks!

Eric
>
> Thanks,
> -Christoffer
>
>> +
>> + its->creadr = reg;
>> +out:
>> + mutex_unlock(&its->cmd_lock);
>> + return ret;
>> +}
>> +
>> #define BASER_INDEX(addr) (((addr) / sizeof(u64)) & 0x7)
>> static unsigned long vgic_mmio_read_its_baser(struct kvm *kvm,
>> struct vgic_its *its,
>> @@ -1317,6 +1344,16 @@ static void vgic_mmio_write_its_ctlr(struct kvm *kvm, struct vgic_its *its,
>> .its_write = wr, \
>> }
>>
>> +#define REGISTER_ITS_DESC_UACCESS(off, rd, wr, uwr, length, acc)\
>> +{ \
>> + .reg_offset = off, \
>> + .len = length, \
>> + .access_flags = acc, \
>> + .its_read = rd, \
>> + .its_write = wr, \
>> + .uaccess_its_write = uwr, \
>> +}
>> +
>> static void its_mmio_write_wi(struct kvm *kvm, struct vgic_its *its,
>> gpa_t addr, unsigned int len, unsigned long val)
>> {
>> @@ -1339,8 +1376,9 @@ static struct vgic_register_region its_registers[] = {
>> REGISTER_ITS_DESC(GITS_CWRITER,
>> vgic_mmio_read_its_cwriter, vgic_mmio_write_its_cwriter, 8,
>> VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
>> - REGISTER_ITS_DESC(GITS_CREADR,
>> - vgic_mmio_read_its_creadr, its_mmio_write_wi, 8,
>> + REGISTER_ITS_DESC_UACCESS(GITS_CREADR,
>> + vgic_mmio_read_its_creadr, its_mmio_write_wi,
>> + vgic_mmio_uaccess_write_its_creadr, 8,
>> VGIC_ACCESS_64bit | VGIC_ACCESS_32bit),
>> REGISTER_ITS_DESC(GITS_BASER,
>> vgic_mmio_read_its_baser, vgic_mmio_write_its_baser, 0x40,
>> --
>> 2.5.5
>>