Re: [PATCH v2 1/4] x86/cpufeatures: Add enumeration for SERIALIZE instruction

[Ricardo Neri <ricardo.neri-calderon@linux.intel.com>]

On Thu, Jul 23, 2020 at 01:02:43AM +0200, Thomas Gleixner wrote:
> Ricardo Neri <ricardo.neri-calderon@linux.intel.com> writes:
> > On Tue, Jul 07, 2020 at 09:36:15AM -0700, Andy Lutomirski wrote:
> >> On Mon, Jul 6, 2020 at 7:21 PM Cathy Zhang <cathy.zhang@intel.com> wrote:
> >> >
> >> > This instruction gives software a way to force the processor to complete
> >> > all modifications to flags, registers and memory from previous instructions
> >> > and drain all buffered writes to memory before the next instruction is
> >> > fetched and executed.
> >> >
> >> > The same effect can be obtained using the cpuid instruction. However,
> >> > cpuid causes modification on the eax, ebx, ecx, and ecx regiters; it
> >> > also causes a VM exit.
> >> >
> >> > A processor supports SERIALIZE instruction if CPUID.0x0x.0x0:EDX[14] is
> >> > present. The CPU feature flag is shown as "serialize" in /proc/cpuinfo.
> >> >
> >> > Detailed information on the instructions and CPUID feature flag SERIALIZE
> >> > can be found in the latest Intel Architecture Instruction Set Extensions
> >> > and Future Features Programming Reference and Intel 64 and IA-32
> >> > Architectures Software Developer's Manual.
> >> 
> >> Can you also wire this up so sync_core() uses it?
> >
> > I am cc'ing Fenghua, who has volunteered to work on this. Addind support
> > for SERIALIZE in sync_core() should not block merging these patches,
> > correct?
> 
> Come on. We are not serving KVM first before making this usable on bare
> metal.

Hi Thomas,

I ended up implementing support for SERIALIZE in sync_core() I will be
posting patches for this in the next few days.

Thanks and BR,
Ricardo