Re: [Qemu-devel] [PATCH 2/2] Expose tsc deadline timer cpuid to guest

[Rik van Riel <riel@redhat.com>]

On 03/09/2012 01:27 PM, Liu, Jinsong wrote:

> As for 'tsc deadline' feature exposing, my patch (as attached) just obey qemu general cpuid exposing method, and also satisfied your target I think.

One question.

Why is TSC_DEADLINE not exposed in the cpuid allowed feature
bits in do_cpuid_ent() in arch/x86/kvm/x86.c ?

         /* cpuid 1.ecx */
         const u32 kvm_supported_word4_x86_features =
                 F(XMM3) | F(PCLMULQDQ) | 0 /* DTES64, MONITOR */ |
                 0 /* DS-CPL, VMX, SMX, EST */ |
                 0 /* TM2 */ | F(SSSE3) | 0 /* CNXT-ID */ | 0 /* 
Reserved */ |
                 F(FMA) | F(CX16) | 0 /* xTPR Update, PDCM */ |
                 0 /* Reserved, DCA */ | F(XMM4_1) |
                 F(XMM4_2) | F(X2APIC) | F(MOVBE) | F(POPCNT) |
                 0 /* Reserved*/ | F(AES) | F(XSAVE) | 0 /* OSXSAVE */ | 
F(AVX) |
                 F(F16C) | F(RDRAND);

Would it make sense to expose F(TSC_DEADLINE) above?

Or is there something truly special about tsc deadline
that means it should be different from everything else?

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