Re: [Xen-devel] [PATCH, v2] linux-2.6.18: add privileged/unprivileged kernel feature indication

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> On 21.07.11 at 11:32, Keir Fraser <keir@xxxxxxx> wrote:
> Aren't XEN_PRIV_CAP_STR parts pointless? Any hypervisor new enough to
> understand those features will also understand
> XEN_ELFNOTE_SUPPORTED_FEATURE?

It's more for completeness (so that when XEN_COMPAT set high enough
one can e.g. inspect the ELF notes without needing to understand binary
values).

Jan

>  -- Keir
> 
> On 19/07/2011 10:14, "Jan Beulich" <JBeulich@xxxxxxxxxx> wrote:
> 
>> This is the kernel side change accompanying the earlier sent Xen side
>> patch titled identically.
>> 
>> (This depends on the public headers to be synced over after the
>> respective hypervisor side change.)
>> 
>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
>> 
>> --- a/arch/i386/kernel/head-xen.S
>> +++ b/arch/i386/kernel/head-xen.S
>> @@ -12,6 +12,7 @@
>>  #include <asm/dwarf2.h>
>>  #include <xen/interface/xen.h>
>>  #include <xen/interface/elfnote.h>
>> +#include <xen/interface/features.h>
>>  
>>  /*
>>   * References to members of the new_cpu_data structure.
>> @@ -142,6 +143,19 @@ ENTRY(cpu_gdt_table)
>> .quad 0x0000000000000000 /* 0xf0 - unused */
>> .quad 0x0000000000000000 /* 0xf8 - GDT entry 31: double-fault TSS */
>>  
>> +#ifdef CONFIG_XEN_UNPRIVILEGED_GUEST
>> +# define XEN_PRIV_CAP  (1 << XENFEAT_unprivileged)
>> +# define XEN_PRIV_CAP_STR "|!unprivileged"
>> +#else
>> +# define XEN_PRIV_CAP  ((1 << XENFEAT_privileged) | \
>> +    (1 << XENFEAT_unprivileged))
>> +# define XEN_PRIV_CAP_STR "|privileged|unprivileged"
>> +#endif
>> +#if CONFIG_XEN_COMPAT < 0xffffffff//temp 0x040200
>> +# undef XEN_PRIV_CAP_STR
>> +# define XEN_PRIV_CAP_STR ""
>> +#endif
>> +
>>  #if CONFIG_XEN_COMPAT <= 0x030002
>>  /*
>>   * __xen_guest information
>> @@ -168,7 +182,8 @@ ENTRY(cpu_gdt_table)
>> utoa (__PAGE_OFFSET + __PHYSICAL_START + VIRT_ENTRY_OFFSET)
>> .ascii ",HYPERCALL_PAGE=0x"
>> utoa ((__PHYSICAL_START+HYPERCALL_PAGE_OFFSET)>>PAGE_SHIFT)
>> - .ascii  ",FEATURES=writable_page_tables"
>> + .ascii  ",FEATURES=" XEN_PRIV_CAP
>> + .ascii          "|writable_page_tables"
>> .ascii          "|writable_descriptor_tables"
>> .ascii          "|auto_translated_physmap"
>> .ascii          "|pae_pgdir_above_4gb"
>> @@ -195,7 +210,18 @@ ENTRY(cpu_gdt_table)
>> ELFNOTE(Xen, XEN_ELFNOTE_ENTRY,          .long,  startup_32)
>> ELFNOTE(Xen, XEN_ELFNOTE_HYPERCALL_PAGE, .long,  hypercall_page)
>> ELFNOTE(Xen, XEN_ELFNOTE_HV_START_LOW,   .long,  HYPERVISOR_VIRT_START)
>> - ELFNOTE(Xen, XEN_ELFNOTE_FEATURES,       .asciz,
>> 
> "writable_page_tables|writable_descriptor_tables|auto_translated_physmap|pae_
> p
>> gdir_above_4gb|supervisor_mode_kernel")
>> + ELFNOTE(Xen, XEN_ELFNOTE_FEATURES,       .ascii, "writable_page_tables";
>> +       .ascii  "|writable_descriptor_tables";
>> +       .ascii  "|auto_translated_physmap";
>> +       .ascii  "|pae_pgdir_above_4gb";
>> +       .ascii  "|supervisor_mode_kernel";
>> +       .asciz  XEN_PRIV_CAP_STR)
>> + ELFNOTE(Xen, XEN_ELFNOTE_SUPPORTED_FEATURES, .long, XEN_PRIV_CAP |
>> +        (1 << XENFEAT_writable_page_tables) |
>> +        (1 << XENFEAT_writable_descriptor_tables) |
>> +        (1 << XENFEAT_auto_translated_physmap) |
>> +        (1 << XENFEAT_pae_pgdir_above_4gb) |
>> +        (1 << XENFEAT_supervisor_mode_kernel))
>>  #ifdef CONFIG_X86_PAE
>> ELFNOTE(Xen, XEN_ELFNOTE_PAE_MODE,       .asciz, "yes")
>> ELFNOTE(Xen, XEN_ELFNOTE_L1_MFN_VALID,   .quad,  
> _PAGE_PRESENT,_PAGE_PRESENT)
>> --- a/arch/x86_64/kernel/head-xen.S
>> +++ b/arch/x86_64/kernel/head-xen.S
>> @@ -24,6 +24,7 @@
>>  #include <asm/cache.h>
>>  #include <asm/dwarf2.h>
>>  #include <xen/interface/elfnote.h>
>> +#include <xen/interface/features.h>
>>  
>> .section .bootstrap.text, "ax", @progbits
>> .code64
>> @@ -160,6 +161,19 @@ gdt_end:
>>  ENTRY(empty_zero_page)
>> .skip PAGE_SIZE
>>  
>> +#ifdef CONFIG_XEN_UNPRIVILEGED_GUEST
>> +# define XEN_PRIV_CAP  (1 << XENFEAT_unprivileged)
>> +# define XEN_PRIV_CAP_STR "|!unprivileged"
>> +#else
>> +# define XEN_PRIV_CAP  ((1 << XENFEAT_privileged) | \
>> +    (1 << XENFEAT_unprivileged))
>> +# define XEN_PRIV_CAP_STR "|privileged|unprivileged"
>> +#endif
>> +#if CONFIG_XEN_COMPAT < 0xffffffff//temp 0x040200
>> +# undef XEN_PRIV_CAP_STR
>> +# define XEN_PRIV_CAP_STR ""
>> +#endif
>> +
>>  #if CONFIG_XEN_COMPAT <= 0x030002
>>  /*
>>   * __xen_guest information
>> @@ -186,7 +200,8 @@ ENTRY(empty_zero_page)
>> utoh (__START_KERNEL_map + __PHYSICAL_START)
>> .ascii ",HYPERCALL_PAGE=0x"
>> utoh (phys_hypercall_page >> PAGE_SHIFT)
>> - .ascii  ",FEATURES=writable_page_tables"
>> + .ascii  ",FEATURES=" XEN_PRIV_CAP
>> + .ascii   "|writable_page_tables"
>> .ascii   "|writable_descriptor_tables"
>> .ascii   "|auto_translated_physmap"
>> .ascii          "|supervisor_mode_kernel"
>> @@ -206,6 +221,15 @@ ENTRY(empty_zero_page)
>> ELFNOTE(Xen, XEN_ELFNOTE_ENTRY,          .quad,  startup_64)
>> ELFNOTE(Xen, XEN_ELFNOTE_HYPERCALL_PAGE, .quad,  hypercall_page)
>> ELFNOTE(Xen, XEN_ELFNOTE_L1_MFN_VALID,   .quad,  
> _PAGE_PRESENT,_PAGE_PRESENT)
>> - ELFNOTE(Xen, XEN_ELFNOTE_FEATURES,       .asciz,
>> 
> "writable_page_tables|writable_descriptor_tables|auto_translated_physmap|supe
> r
>> visor_mode_kernel")
>> + ELFNOTE(Xen, XEN_ELFNOTE_FEATURES,       .ascii, "writable_page_tables";
>> +       .ascii  "|writable_descriptor_tables";
>> +       .ascii  "|auto_translated_physmap";
>> +       .ascii  "|supervisor_mode_kernel";
>> +       .asciz  XEN_PRIV_CAP_STR)
>> + ELFNOTE(Xen, XEN_ELFNOTE_SUPPORTED_FEATURES, .long, XEN_PRIV_CAP |
>> +        (1 << XENFEAT_writable_page_tables) |
>> +        (1 << XENFEAT_writable_descriptor_tables) |
>> +        (1 << XENFEAT_auto_translated_physmap) |
>> +        (1 << XENFEAT_supervisor_mode_kernel))
>> ELFNOTE(Xen, XEN_ELFNOTE_LOADER,         .asciz, "generic")
>> ELFNOTE(Xen, XEN_ELFNOTE_SUSPEND_CANCEL, .long,  1)
>> 
>> 
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@xxxxxxxxxxxxxxxxxxx 
>> http://lists.xensource.com/xen-devel 



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