Re: [Xen-devel] [RFC][PATCH 4/5] tools:firmware:hvmloader: reserve RMRR mappings in e820

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

On 2014/8/9 5:47, Tian, Kevin wrote:
> > From: Chen, Tiejun
> > Sent: Thursday, August 07, 2014 4:03 AM
> >
> > We need to reserve all RMRR mappings in e820 to avoid any
> > potential guest memory conflict.
> strictly speaking besides reserving in e820, you should also poke later
> MMIO BAR allocations to avoid confliction too. Currently it's relative
> to low_mem_pgend, which is likely to be different from host layout
low_mem_pgend is already in e820 so this is checked as well when we try 
to insert RMRR maps into GS e820.
Thanks
Tiejun

> so it's still possible to see a virtual MMIO bar base conflicting to the
> RMRR ranges which are supposed to be sparse.
>
> Thanks
> Kevin
>
> > Signed-off-by: Tiejun Chen <tiejun.chen@xxxxxxxxx>
> > ---
> >   tools/firmware/hvmloader/e820.c | 14 ++++++++++++++
> >   tools/firmware/hvmloader/e820.h |  6 ++++++
> >   tools/firmware/hvmloader/util.c | 13 +++++++++++++
> >   tools/firmware/hvmloader/util.h |  1 +
> >   4 files changed, 34 insertions(+)
> >
> > diff --git a/tools/firmware/hvmloader/e820.c
> > b/tools/firmware/hvmloader/e820.c
> > index 2e05e93..8cf8c75 100644
> > --- a/tools/firmware/hvmloader/e820.c
> > +++ b/tools/firmware/hvmloader/e820.c
> > @@ -74,6 +74,8 @@ int build_e820_table(struct e820entry *e820,
> >                        unsigned int bios_image_base)
> >   {
> >       unsigned int nr = 0;
> > +    struct e820map *e820_rmrr_map;
> > +    unsigned int i = 0;
> >
> >       if ( !lowmem_reserved_base )
> >               lowmem_reserved_base = 0xA0000;
> > @@ -124,6 +126,18 @@ int build_e820_table(struct e820entry *e820,
> >       e820[nr].type = E820_RAM;
> >       nr++;
> >
> > +    /* We'd better reserve RMRR mapping for each VM to avoid potential
> > +     * memory conflict.
> > +     */
> > +    e820_rmrr_map = get_rmrr_map_info();
> > +    for ( i = 0; i <= e820_rmrr_map->nr_map; i++ )
> > +    {
> > +        e820[nr].addr = e820_rmrr_map->map[i].addr;
> > +        e820[nr].size = e820_rmrr_map->map[i].size + 1;
> > +        e820[nr].type = E820_RESERVED;
> > +        nr++;
> > +    }
> > +
> >       /*
> >        * Explicitly reserve space for special pages.
> >        * This space starts at RESERVED_MEMBASE an extends to cover
> > various
> > diff --git a/tools/firmware/hvmloader/e820.h
> > b/tools/firmware/hvmloader/e820.h
> > index b2ead7f..ae4cc55 100644
> > --- a/tools/firmware/hvmloader/e820.h
> > +++ b/tools/firmware/hvmloader/e820.h
> > @@ -15,6 +15,12 @@ struct e820entry {
> >       uint32_t type;
> >   } __attribute__((packed));
> >
> > +#define E820MAX 128
> > +
> > +struct e820map {
> > +    int nr_map;
> > +    struct e820entry map[E820MAX];
> > +};
> >   #endif /* __HVMLOADER_E820_H__ */
> >
> >   /*
> > diff --git a/tools/firmware/hvmloader/util.c b/tools/firmware/hvmloader/util.c
> > index 80d822f..270700f 100644
> > --- a/tools/firmware/hvmloader/util.c
> > +++ b/tools/firmware/hvmloader/util.c
> > @@ -766,6 +766,19 @@ struct shared_info *get_shared_info(void)
> >       return shared_info;
> >   }
> >
> > +struct e820map *get_rmrr_map_info(void)
> > +{
> > +    static struct e820map *e820_map = NULL;
> > +
> > +    if ( e820_map != NULL )
> > +        return e820_map;
> > +
> > +    if ( hypercall_memory_op(XENMEM_RMRR_memory_map,
> > e820_map) != 0 )
> > +        BUG();
> > +
> > +    return e820_map;
> > +}
> > +
> >   uint16_t get_cpu_mhz(void)
> >   {
> >       struct shared_info *shared_info = get_shared_info();
> > diff --git a/tools/firmware/hvmloader/util.h
> > b/tools/firmware/hvmloader/util.h
> > index a70e4aa..26bfb8c 100644
> > --- a/tools/firmware/hvmloader/util.h
> > +++ b/tools/firmware/hvmloader/util.h
> > @@ -236,6 +236,7 @@ unsigned long create_pir_tables(void);
> >   void smp_initialise(void);
> >
> >   #include "e820.h"
> > +struct e820map *get_rmrr_map_info(void);
> >   int build_e820_table(struct e820entry *e820,
> >                        unsigned int lowmem_reserved_base,
> >                        unsigned int bios_image_base);
> > --
> > 1.9.1
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