[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 2/2] x86: drop cpu_has_sse{,2}
On 09/12/16 13:28, Jan Beulich wrote: >>>> On 09.12.16 at 14:00, <andrew.cooper3@xxxxxxxxxx> wrote: >> On 09/12/16 11:54, Jan Beulich wrote: >>> Commit dc88221c97 ("x86: rename XMM* features to SSE*") pointlessly >>> added them - these features are always available on 64-bit CPUs. (Let's >>> not assume this for MMX though in at least the insn emulator.) >>> >>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> >> This isn't necessarily true when compiled for 32bit in the userspace >> harness. > In the test harness vcpu_has_* == cpu_has_*, as also > demonstrated by > > #define host_and_vcpu_must_have(feat) vcpu_must_have(feat) > > . The change (as its title is trying to say) really only affects the > hypervisor. Right, but this change is still contrary to the written requirement. /* * Note the difference between vcpu_must_have_<feature>() and * host_and_vcpu_must_have(<feature>): The latter needs to be used when * emulation code is using the same instruction class for carrying out * the actual operation. */ We are using SSE and SSE2 instructions for carrying out that emulation, so should still be using the host_and_vcpu check. Swapping the hypervisor defines to being 1 will cause the generate_exception_if() clause to become dead and get dropped, turning host_and_vcpu_must_have() into just vcpu_must_have_##feat ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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