[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH RFC 20/31] x86: Improvements to in-hypervisor cpuid sanity checks
>>> On 21.01.16 at 19:15, <andrew.cooper3@xxxxxxxxxx> wrote: > On 21/01/16 17:21, Andrew Cooper wrote: >> On 21/01/16 17:02, Jan Beulich wrote: >>>>>> On 16.12.15 at 22:24, <andrew.cooper3@xxxxxxxxxx> wrote: >>>> case 0x80000001: >>>> - /* Modify Feature Information. */ >>>> - if ( is_pv_32bit_domain(currd) ) >>>> - { >>>> - __clear_bit(X86_FEATURE_LM % 32, &d); >>>> - __clear_bit(X86_FEATURE_LAHF_LM % 32, &c); >>>> - } >>>> - if ( is_pv_32bit_domain(currd) && >>>> - boot_cpu_data.x86_vendor != X86_VENDOR_AMD ) >>>> - __clear_bit(X86_FEATURE_SYSCALL % 32, &d); >>> But what about these 32-bit specific removals? >> LM, from the deep feature dependency removal in libxc, when it is known >> that the domain is 32bit. >> >> For SYSCALL, as far as I can tell, the logic is wrong. 32bit compat >> mode code on Intel can use SYSCALL, as Xen is running in Long mode. >> (This is opposite to the AMD case where 32bit compat code cannot use >> SYSENTER, because Xen is in Long mode.) > > I have just double checked. 32bit PV guests on Intel definitely can use > syscall. Double checked where? As just said in the other mail, I can't find documentation of CSTAR being implemented anywhere in SDM Vol 3. Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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