Re: [PULL 55/63] kvm: handle KVM_EXIT_MEMORY_FAULT

[Paolo Bonzini]

On Fri, Apr 26, 2024 at 3:40 PM Peter Maydell <peter.maydell@linaro.org> wrote:
> > +    addr = memory_region_get_ram_ptr(mr) + section.offset_within_region;
> > +    rb = qemu_ram_block_from_host(addr, false, &offset);
>
> ...and this call to qemu_ram_block_from_host() will only initialize
> offset if it does not fail (i.e. doesn't return NULL)...
>
> I think this code should either handle the case where
> qemu_ram_block_from_host() fails, or, if it is impossible
> for it to fail in this situation, add an assert() and a
> comment about why we know it can't fail.

The assertion is in memory_region_get_ram_ptr(), but Coverity
understandably cannot see it.

Similar to other code in hw/virtio/virtio-balloon.c, this code is
using memory_region_get_ram_ptr() as a roundabout way to go from
MemoryRegion (in this case MemoryRegionSection) to RAMBlock.  The
right fix is to introduce memory_region_get_ram_block() and use it.

Paolo