Re: [Xen-devel] [PATCH 1/2] x86/tboot: invalidate FIX_TBOOT_MAP_ADDRESS mapping after use

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 05.03.15 at 05:45, <gang.wei@xxxxxxxxx> wrote:
> On Feb 18, 2015 17:03, Jan Beulich wrote:
>> In order for commit cbeeaa7d ("x86/nmi: fix shootdown of pcpus
>> running in VMX non-root mode")'s re-use of that fixmap entry to not
>> cause undesirable (in crash context) cross-CPU TLB flushes, invalidate
>> the fixmap entry right after use.
>> 
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>> 
>> --- a/xen/arch/x86/tboot.c
>> +++ b/xen/arch/x86/tboot.c
>> @@ -138,6 +138,7 @@ void __init tboot_probe(void)
>>                        TXT_PUB_CONFIG_REGS_BASE + TXTCR_SINIT_BASE);
>>                        tboot_copy_memory((unsigned char *)&sinit_size,
>>                        sizeof(sinit_size), TXT_PUB_CONFIG_REGS_BASE +
>>                        TXTCR_SINIT_SIZE);
>> +    __set_fixmap(FIX_TBOOT_MAP_ADDRESS, 0, 0);
>>  }
>>  
>>  /* definitions from xen/drivers/passthrough/vtd/iommu.h
>> @@ -476,6 +477,8 @@ int __init tboot_parse_dmar_table(acpi_t
>>      dmar_table_raw = xmalloc_array(unsigned char, dmar_table_length);
>>      tboot_copy_memory(dmar_table_raw, dmar_table_length, pa);
>>      dmar_table = (struct acpi_table_header *)dmar_table_raw;
>> +    __set_fixmap(FIX_TBOOT_MAP_ADDRESS, 0, 0);
>> +
>>      rc = dmar_handler(dmar_table);
>>      xfree(dmar_table_raw);
>> 
>>
> 
> It might be better to move the fixmap invalidations into tboot_copy_memory 
> like below.

I considered this, but dropped the idea due to resulting in several
redundant invalidations.

Jan


_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
http://lists.xen.org/xen-devel