Re: [PATCH v3 1/4] tpm: mark correct memory region range dirty when clearing RAM

[Peter Xu]

On Mon, Jul 26, 2021 at 06:03:43PM +0200, David Hildenbrand wrote:
> We might not start at the beginning of the memory region. Let's
> calculate the offset into the memory region via the difference in the
> host addresses.
> 
> Acked-by: Stefan Berger <stefanb@linux.ibm.com>
> Fixes: ffab1be70692 ("tpm: clear RAM when "memory overwrite" requested")
> Cc: Marc-André Lureau <marcandre.lureau@redhat.com>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: "Michael S. Tsirkin" <mst@redhat.com>
> Cc: Eduardo Habkost <ehabkost@redhat.com>
> Cc: Alex Williamson <alex.williamson@redhat.com>
> Cc: Dr. David Alan Gilbert <dgilbert@redhat.com>
> Cc: Igor Mammedov <imammedo@redhat.com>
> Cc: Claudio Fontana <cfontana@suse.de>
> Cc: Thomas Huth <thuth@redhat.com>
> Cc: "Alex Bennée" <alex.bennee@linaro.org>
> Cc: Peter Xu <peterx@redhat.com>
> Cc: Laurent Vivier <lvivier@redhat.com>
> Cc: Stefan Berger <stefanb@linux.vnet.ibm.com>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  hw/tpm/tpm_ppi.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/tpm/tpm_ppi.c b/hw/tpm/tpm_ppi.c
> index 362edcc5c9..f243d9d0f6 100644
> --- a/hw/tpm/tpm_ppi.c
> +++ b/hw/tpm/tpm_ppi.c
> @@ -30,11 +30,14 @@ void tpm_ppi_reset(TPMPPI *tpmppi)
>          guest_phys_blocks_init(&guest_phys_blocks);
>          guest_phys_blocks_append(&guest_phys_blocks);
>          QTAILQ_FOREACH(block, &guest_phys_blocks.head, next) {
> +            hwaddr mr_offs = (uint8_t *)memory_region_get_ram_ptr(block->mr) 
> -
> +                             block->host_addr;

Didn't look closely previous - should it be reversed instead?

  block->host_addr - memory_region_get_ram_ptr(block->mr)

Thanks,

> +
>              trace_tpm_ppi_memset(block->host_addr,
>                                   block->target_end - block->target_start);
>              memset(block->host_addr, 0,
>                     block->target_end - block->target_start);
> -            memory_region_set_dirty(block->mr, 0,
> +            memory_region_set_dirty(block->mr, mr_offs,
>                                      block->target_end - block->target_start);
>          }
>          guest_phys_blocks_free(&guest_phys_blocks);
> -- 
> 2.31.1
> 

-- 
Peter Xu