Re: [Xen-devel] [PATCH 1/2] VT-d: check all of an RMRR for being E820-reserved

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Thu, Feb 06, 2020 at 02:31:03PM +0100, Jan Beulich wrote:
> Checking just the first and last page is not sufficient (and redundant
> for single-page regions). As we don't need to care about IA64 anymore,
> use an x86-specific function to get this done without looping over each
> individual page.
> 
> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
> 
> --- a/xen/drivers/passthrough/vtd/dmar.c
> +++ b/xen/drivers/passthrough/vtd/dmar.c
> @@ -29,6 +29,7 @@
>  #include <xen/pci.h>
>  #include <xen/pci_regs.h>
>  #include <asm/atomic.h>
> +#include <asm/e820.h>
>  #include <asm/string.h>
>  #include "dmar.h"
>  #include "iommu.h"
> @@ -632,14 +633,11 @@ acpi_parse_one_rmrr(struct acpi_dmar_hea
>       * not properly represented in the system memory map and
>       * inform the user
>       */
> -    if ( (!page_is_ram_type(paddr_to_pfn(base_addr), RAM_TYPE_RESERVED)) ||
> -         (!page_is_ram_type(paddr_to_pfn(end_addr), RAM_TYPE_RESERVED)) )
> -    {
> +    if ( !e820_all_mapped(base_addr, end_addr + 1, RAM_TYPE_RESERVED) )

Do you need to add one to the end?

The other user of e820_all_mapped seems to treat end as start + size
- 1, which makes me think the parameters to the function are an
inclusive range [start, end] and that's what's present in the RMRR
ACPI entries?

Thanks, Roger.

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