On 29 October 2018 at 15:13, Peter Maydell <[email protected]> wrote: > On 24 October 2018 at 12:37, Richard Henderson > <[email protected]> wrote: >> Signed-off-by: Richard Henderson <[email protected]> >> --- >> target/arm/kvm32.c | 33 ++++++++++++++++++++++++++++----- >> 1 file changed, 28 insertions(+), 5 deletions(-) > > Reviewed-by: Peter Maydell <[email protected]> > >> + /* >> + * FIXME: There is not yet a way to read MVFR2. >> + * Fortunately there is not yet anything in there that affects >> migration. >> + */ > > We should bring that up with the KVM folks (cc'd)... > > Presumably KVM_REG_ARM_VFP_MVFR2 should be 0x1005 and the code > in the kernel for handling this bit of the get/set-one-reg > ioctls needs to have code for it (including returning 0 > for v7 CPUs, where this VMRS register encoding was UNPREDICTABLE).
There's an argument for "fail the ioctl on v7 CPUs" rather than "return 0"; I don't think I have a strong opinion, since in practice userspace needs to handle the "doesn't exist" case when it's running on an older kernel anyway. thanks -- PMM
