Re: [Xen-devel] [PATCH RFC 32/35] arm : acpi map xen environment table to dom0

[Julien Grall <julien.grall@xxxxxxxxxx>]

Hi Stefano,

On 06/02/2015 01:36, Stefano Stabellini wrote:
> On Wed, 4 Feb 2015, parth.dixit@xxxxxxxxxx wrote:
> > From: Parth Dixit <parth.dixit@xxxxxxxxxx>
> >
> > xen environment table contains the grant table address,size and event
> > channel interrupt information required by dom0.
> >
> > Signed-off-by: Parth Dixit <parth.dixit@xxxxxxxxxx>
> > ---
> >   xen/arch/arm/arm64/acpi/arm-core.c | 52 +++++++++++++++++++++++++++++++++++++-
> >   1 file changed, 51 insertions(+), 1 deletion(-)
> >
> > diff --git a/xen/arch/arm/arm64/acpi/arm-core.c 
> > b/xen/arch/arm/arm64/acpi/arm-core.c
> > index 9fd02f9..9e9285c 100644
> > --- a/xen/arch/arm/arm64/acpi/arm-core.c
> > +++ b/xen/arch/arm/arm64/acpi/arm-core.c
> > @@ -33,7 +33,6 @@
> >   #include <asm/cputype.h>
> >   #include <asm/acpi.h>
> >   #include <asm/p2m.h>
> > -
> >   /*
> >    * We never plan to use RSDT on arm/arm64 as its deprecated in spec but this
> >    * variable is still required by the ACPI core
> Spurious change
>
>
> > @@ -297,6 +296,49 @@ static int map_stao_table(struct domain *d, u64 *mstao)
> >       return 0;
> >   }
> >
> > +static int map_xenv_table(struct domain *d, u64 *mxenv)
> > +{
> > +    u64 addr;
> > +    u64 size;
> > +    int res;
> > +    u8 checksum;
> > +    struct acpi_table_xenv *xenv=NULL;
> > +
> > +    xenv = ACPI_ALLOCATE_ZEROED( sizeof(struct acpi_table_xenv) );
> > +    if( xenv == NULL )
> > +            return -ENOMEM;
> > +
> > +    ACPI_MEMCPY(xenv->header.signature, ACPI_SIG_XENV, 4);
> > +    xenv->header.length = sizeof(struct acpi_table_header)+12;
> > +    xenv->header.checksum = 0;
> > +    ACPI_MEMCPY(xenv->header.oem_id, "XenVMM", 6);
> > +    ACPI_MEMCPY(xenv->header.oem_table_id, "RTSMVEV8", 8);
> > +    xenv->header.revision = 1;
> > +    ACPI_MEMCPY(xenv->header.asl_compiler_id, "INTL", 4);
> > +    xenv->header.asl_compiler_revision = 0x20140828;
> > +    xenv->gnt_start = 0x00000010000000;
> > +    xenv->gnt_size = 0x20000;
> > +    xenv->evt_intr = 31;
> > +    xenv->evt_intr_flag =3;
> > +    size = sizeof(struct acpi_table_xenv);
> As per all the other checksum calculation, I wonder whether we need a
> memory barrier here.
I don't see why the memory barrier is necessary, the checksum and the 
modification of the table is done on the same processor.
But cleaning/invalidate the cache after the checksum may be required.

Regards,

--
Julien Grall

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