On Sat, 13 Jul 2019 at 18:40, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > > On 11/07/19 07:49, Jing Liu wrote: > > AVX512 BFLOAT16 instructions support 16-bit BFLOAT16 floating-point > > format (BF16) for deep learning optimization. > > > > Intel adds AVX512 BFLOAT16 feature in CooperLake, which is CPUID.7.1.EAX[5]. > > > > Detailed information of the CPUID bit can be found here, > > https://software.intel.com/sites/default/files/managed/c5/15/\ > > architecture-instruction-set-extensions-programming-reference.pdf. > > > > Signed-off-by: Jing Liu <jing2.liu@xxxxxxxxxxxxxxx> > > --- > > > > This patch depends on kernel patch https://lkml.org/lkml/2019/6/19/912 > > and Paolo's patch set https://lkml.org/lkml/2019/7/4/468. > > > > arch/x86/kvm/cpuid.c | 12 +++++++++++- > > 1 file changed, 11 insertions(+), 1 deletion(-) > > > > diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c > > index 8fc6039..0c125dd 100644 > > --- a/arch/x86/kvm/cpuid.c > > +++ b/arch/x86/kvm/cpuid.c > > @@ -358,9 +358,13 @@ static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry, int index) > > F(SPEC_CTRL_SSBD) | F(ARCH_CAPABILITIES) | F(INTEL_STIBP) | > > F(MD_CLEAR); > > > > + /* cpuid 7.1.eax */ > > + const u32 kvm_cpuid_7_1_eax_x86_features = > > + F(AVX512_BF16); > > + > > switch (index) { > > case 0: > > - entry->eax = 0; > > + entry->eax = min(entry->eax, 1); > > entry->ebx &= kvm_cpuid_7_0_ebx_x86_features; > > cpuid_mask(&entry->ebx, CPUID_7_0_EBX); > > /* TSC_ADJUST is emulated */ > > @@ -384,6 +388,12 @@ static inline void do_cpuid_7_mask(struct kvm_cpuid_entry2 *entry, int index) > > */ > > entry->edx |= F(ARCH_CAPABILITIES); > > break; > > + case 1: > > + entry->eax &= kvm_cpuid_7_1_eax_x86_features; > > + entry->ebx = 0; > > + entry->ecx = 0; > > + entry->edx = 0; > > + break; > > default: > > WARN_ON_ONCE(1); > > entry->eax = 0; > > > > Queued, thanks. I see this in kvm/queue: In file included from ./include/linux/list.h:9:0, from ./include/linux/preempt.h:11, from ./include/linux/hardirq.h:5, from ./include/linux/kvm_host.h:7, from /home/kernel/data/kvm/arch/x86/kvm//cpuid.c:12: /home/kernel/data/kvm/arch/x86/kvm//cpuid.c: In function ‘do_cpuid_7_mask’: ./include/linux/kernel.h:819:29: warning: comparison of distinct pointer types lacks a cast (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1))) ^ ./include/linux/kernel.h:833:4: note: in expansion of macro ‘__typecheck’ (__typecheck(x, y) && __no_side_effects(x, y)) ^ ./include/linux/kernel.h:843:24: note: in expansion of macro ‘__safe_cmp’ __builtin_choose_expr(__safe_cmp(x, y), \ ^ ./include/linux/kernel.h:852:19: note: in expansion of macro ‘__careful_cmp’ #define min(x, y) __careful_cmp(x, y, <) ^ /home/kernel/data/kvm/arch/x86/kvm//cpuid.c:377:16: note: in expansion of macro ‘min’ entry->eax = min(entry->eax, 1); ^
