On 04/12/2019 10:06, Jan Beulich wrote:
> On 04.12.2019 10:43, Andrew Cooper wrote:
>> The vmcb is zeroed on allocate - drop all explicit writes of 0. Move
>> hvm_update_guest_efer() to co-locate it with the other control register
>> updates.
>>
>> Move the BUILD_BUG_ON() into build_assertions(), and add some offset checks
>> for fields after the large blocks of reserved fields (as these are the most
>> likely to trigger from a mis-edit). Take the opportunity to fold 6 adjacent
>> res* fields into one.
>>
>> Finally, drop all trailing whitespace in the file.
>>
>> Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com>
> Reviewed-by: Jan Beulich <jbeul...@suse.com>
> albeit with two (optional) suggestions:
>
>> @@ -297,14 +258,26 @@ void __init setup_vmcb_dump(void)
>>
>> static void __init __maybe_unused build_assertions(void)
>> {
>> - struct segment_register sreg;
>> + struct vmcb_struct vmcb;
>> +
>> + /* Build-time check of the VMCB layout. */
>> + BUILD_BUG_ON(sizeof(vmcb) != PAGE_SIZE);
>> + BUILD_BUG_ON(offsetof(struct vmcb_struct, _pause_filter_thresh) !=
>> 0x03c);
>> + BUILD_BUG_ON(offsetof(struct vmcb_struct, _vintr) !=
>> 0x060);
>> + BUILD_BUG_ON(offsetof(struct vmcb_struct, eventinj) !=
>> 0x0a8);
>> + BUILD_BUG_ON(offsetof(struct vmcb_struct, es) !=
>> 0x400);
>> + BUILD_BUG_ON(offsetof(struct vmcb_struct, _cpl) !=
>> 0x4cb);
>> + BUILD_BUG_ON(offsetof(struct vmcb_struct, _cr4) !=
>> 0x548);
>> + BUILD_BUG_ON(offsetof(struct vmcb_struct, rsp) !=
>> 0x5d8);
>> + BUILD_BUG_ON(offsetof(struct vmcb_struct, rax) !=
>> 0x5f8);
>> + BUILD_BUG_ON(offsetof(struct vmcb_struct, _g_pat) !=
>> 0x668);
>>
>> /* Check struct segment_register against the VMCB segment layout. */
>> - BUILD_BUG_ON(sizeof(sreg) != 16);
>> - BUILD_BUG_ON(sizeof(sreg.sel) != 2);
>> - BUILD_BUG_ON(sizeof(sreg.attr) != 2);
>> - BUILD_BUG_ON(sizeof(sreg.limit) != 4);
>> - BUILD_BUG_ON(sizeof(sreg.base) != 8);
>> + BUILD_BUG_ON(sizeof(vmcb.es) != 16);
>> + BUILD_BUG_ON(sizeof(vmcb.es.sel) != 2);
>> + BUILD_BUG_ON(sizeof(vmcb.es.attr) != 2);
>> + BUILD_BUG_ON(sizeof(vmcb.es.limit) != 4);
>> + BUILD_BUG_ON(sizeof(vmcb.es.base) != 8);
>> BUILD_BUG_ON(offsetof(struct segment_register, sel) != 0);
>> BUILD_BUG_ON(offsetof(struct segment_register, attr) != 2);
>> BUILD_BUG_ON(offsetof(struct segment_register, limit) != 4);
> For the ones only supplying context here, how about using the
> shorter offsetof(typeof(vmcb.es), ...), also tying things better
> to the prior sizeof() checks? The same, albeit to a lesser degree,
> might then go for the earlier block, which could use the shorter
> typeof(vmcb).
Fixed.
>
>> --- a/xen/include/asm-x86/hvm/svm/vmcb.h
>> +++ b/xen/include/asm-x86/hvm/svm/vmcb.h
>> @@ -406,12 +406,7 @@ struct vmcb_struct {
>> u32 _exception_intercepts; /* offset 0x08 - cleanbit 0 */
>> u32 _general1_intercepts; /* offset 0x0C - cleanbit 0 */
>> u32 _general2_intercepts; /* offset 0x10 - cleanbit 0 */
>> - u32 res01; /* offset 0x14 */
>> - u64 res02; /* offset 0x18 */
>> - u64 res03; /* offset 0x20 */
>> - u64 res04; /* offset 0x28 */
>> - u64 res05; /* offset 0x30 */
>> - u32 res06; /* offset 0x38 */
>> + u32 res01[10];
> Was it intentional for the comment to be lost altogether?
Yes. The offset is trivial (0x10 + sizeof(u32)) and of no interest.
Omitting it increases readability by helping to highlight where the
reserved blocks are.
~Andrew
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