Re: [Xen-devel] [v8][PATCH 06/17] tools/libxc: check if modules space is overlapping with reserved device memory

["Chen, Tiejun" <tiejun.chen@xxxxxxxxx>]

On 2014/12/3 3:55, Konrad Rzeszutek Wilk wrote:
> On Mon, Dec 01, 2014 at 05:24:24PM +0800, Tiejun Chen wrote:
> > In case of reserved device memory overlapping with ram, it also probably
> s/also//
Fixed.

> > overlap with modules space so we need to check these reserved device
> s/overlap/overlaps/
Fixed.

> What is 'modules space'?
Please see modules_init(), and looks it includs acpi and smbios currently.

> > memory as well.
> s/reserved device memory/E820_RSV/ ?
I don't find we have such a definition.

> > Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
> > ---
> >   tools/libxc/xc_hvm_build_x86.c | 94 +++++++++++++++++++++++++++++++++++-------
> >   1 file changed, 79 insertions(+), 15 deletions(-)
> >
> > diff --git a/tools/libxc/xc_hvm_build_x86.c b/tools/libxc/xc_hvm_build_x86.c
> > index c81a25b..ddcf06d 100644
> > --- a/tools/libxc/xc_hvm_build_x86.c
> > +++ b/tools/libxc/xc_hvm_build_x86.c
> > @@ -54,9 +54,82 @@
> >
> >   #define VGA_HOLE_SIZE (0x20)
> >
> > +/*
> > + * Check whether there exists mmio hole in the specified memory range.
> > + * Returns 1 if exists, else returns 0.
> > + */
> > +static int check_mmio_hole(uint64_t start, uint64_t memsize,
> > +                           uint64_t mmio_start, uint64_t mmio_size)
> > +{
> > +    if ( start + memsize <= mmio_start || start >= mmio_start + mmio_size )
> > +        return 0;
> > +    else
> > +        return 1;
> > +}
> > +
> > +/* Getting all reserved device memory map info. */
> > +static struct xen_reserved_device_memory
> > +*xc_get_reserved_device_memory_map(xc_interface *xch, unsigned int nr_entries,
> > +                                   uint32_t dom)
> > +{
> > +    struct xen_reserved_device_memory *xrdm = NULL;
> > +    int rc = xc_reserved_device_memory_map(xch, dom, xrdm, &nr_entries);
> > +
> > +    if ( rc < 0 )
> > +    {
> > +        if ( errno == ENOBUFS )
> > +        {
> > +            if ( (xrdm = malloc(nr_entries *
> > +                                sizeof(xen_reserved_device_memory_t))) == NULL 
> > )
> > +            {
> > +                PERROR("Could not allocate memory.");
> > +                return 0;
> > +            }
> > +            rc = xc_reserved_device_memory_map(xch, dom, xrdm, &nr_entries);
> > +            if ( rc )
> > +            {
> > +                PERROR("Could not get reserved device memory maps.");
> > +                free(xrdm);
> > +                return 0;
> Uhhh, is that the right error to return?
>
> Don't you mean ERR_PTR logic? Or 'return NULL' ?
OOPS, return NULL.

> > +            }
> > +        }
> > +        else
> > +            PERROR("Could not get reserved device memory maps.");
> > +    }
> > +
> > +    return xrdm;
> > +}
> > +
> > +static int xc_check_modules_space(xc_interface *xch, uint64_t *mstart_out,
> > +                                  uint64_t *mend_out, uint32_t dom)
> > +{
> > +    unsigned int i = 0, nr_entries = 0;
> > +    uint64_t rdm_start = 0, rdm_end = 0;
> > +    struct xen_reserved_device_memory *rdm_map =
> > +                        xc_get_reserved_device_memory_map(xch, nr_entries, 
> > dom);
> > +
> You need to check whether 'rdm_map' is NULL.
You're right.

Actually nr_entries is always 0 if rdm_map is NULL with my original 
design. But now this should be checked as you mentioned, so
+    if ( !rdm_map )
+        return 0;
+

> > +    for ( i = 0; i < nr_entries; i++ )
> > +    {
> > +        rdm_start = (uint64_t)rdm_map[i].start_pfn << XC_PAGE_SHIFT;
> > +        rdm_end = rdm_start + ((uint64_t)rdm_map[i].nr_pages << XC_PAGE_SHIFT);
> > +
> > +        /* Just use check_mmio_hole() to check modules ranges. */
> > +        if ( check_mmio_hole(rdm_start,
> > +                             rdm_end - rdm_start,
> > +                             *mstart_out, *mend_out) )
> > +            return -1;
> > +    }
> > +
> > +    free(rdm_map);
> > +
> > +    return 0;
> > +}
> > +
> >   static int modules_init(struct xc_hvm_build_args *args,
> >                           uint64_t vend, struct elf_binary *elf,
> > -                        uint64_t *mstart_out, uint64_t *mend_out)
> > +                        uint64_t *mstart_out, uint64_t *mend_out,
> > +                        xc_interface *xch,
> > +                        uint32_t dom)
> >   {
> >   #define MODULE_ALIGN 1UL << 7
> >   #define MB_ALIGN     1UL << 20
> > @@ -80,6 +153,10 @@ static int modules_init(struct xc_hvm_build_args *args,
> >       if ( *mend_out > vend )
> >           return -1;
> >
> > +    /* Is it overlapping with reserved device memory? */
> > +    if ( xc_check_modules_space(xch, mstart_out, mend_out, dom) )
> > +        return -1;
> > +
> >       if ( args->acpi_module.length != 0 )
> >           args->acpi_module.guest_addr_out = *mstart_out;
> >       if ( args->smbios_module.length != 0 )
> > @@ -226,19 +303,6 @@ static int loadmodules(xc_interface *xch,
> >       return rc;
> >   }
> >
> > -/*
> > - * Check whether there exists mmio hole in the specified memory range.
> > - * Returns 1 if exists, else returns 0.
> > - */
> > -static int check_mmio_hole(uint64_t start, uint64_t memsize,
> > -                           uint64_t mmio_start, uint64_t mmio_size)
> > -{
> > -    if ( start + memsize <= mmio_start || start >= mmio_start + mmio_size )
> > -        return 0;
> > -    else
> > -        return 1;
> > -}
> > -
> This movement of 'check_mmio_hole' needs to be a seperate patch.
Okay.

Thanks
Tiejun

> >   static int setup_guest(xc_interface *xch,
> >                          uint32_t dom, struct xc_hvm_build_args *args,
> >                          char *image, unsigned long image_size)
> > @@ -282,7 +346,7 @@ static int setup_guest(xc_interface *xch,
> >           goto error_out;
> >       }
> >
> > -    if ( modules_init(args, v_end, &elf, &m_start, &m_end) != 0 )
> > +    if ( modules_init(args, v_end, &elf, &m_start, &m_end, xch, dom) != 0 )
> >       {
> >           ERROR("Insufficient space to load modules.");
> >           goto error_out;
> > --
> > 1.9.1
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