| Message ID | 1374572465-15278-1-git-send-email-jasowang@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On 07/23/2013 02:41 AM, Jason Wang wrote: > > +static inline uint32_t hypervisor_cpuid_base(const char *sig, uint32_t leaves) > +{ > + uint32_t base, eax, ebx, ecx, edx; > + char signature[13]; > + > + for (base = 0x40000000; base < 0x40010000; base += 0x100) { > + cpuid(base, &eax, &ebx, &ecx, &edx); > + *(uint32_t *)(signature + 0) = ebx; > + *(uint32_t *)(signature + 4) = ecx; > + *(uint32_t *)(signature + 8) = edx; > + signature[12] = 0; > + > + if (!strcmp(sig, signature) && > + (leaves == 0 || ((eax - base) >= leaves))) > + return base; > + } > + > + return 0; > +} > + Hmm... how about: uint32_t sign[3]; cpuid(base, &eax, &sign[0], &sign[1], &sign[2]); if (!memcmp(sig, sign, 12) && ...); -hpa -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Il 23/07/2013 12:04, H. Peter Anvin ha scritto: > On 07/23/2013 02:41 AM, Jason Wang wrote: >> >> +static inline uint32_t hypervisor_cpuid_base(const char *sig, uint32_t leaves) >> +{ >> + uint32_t base, eax, ebx, ecx, edx; >> + char signature[13]; >> + >> + for (base = 0x40000000; base < 0x40010000; base += 0x100) { >> + cpuid(base, &eax, &ebx, &ecx, &edx); >> + *(uint32_t *)(signature + 0) = ebx; >> + *(uint32_t *)(signature + 4) = ecx; >> + *(uint32_t *)(signature + 8) = edx; >> + signature[12] = 0; >> + >> + if (!strcmp(sig, signature) && >> + (leaves == 0 || ((eax - base) >= leaves))) >> + return base; >> + } >> + >> + return 0; >> +} >> + > > Hmm... how about: > > uint32_t sign[3]; > > cpuid(base, &eax, &sign[0], &sign[1], &sign[2]); > > if (!memcmp(sig, sign, 12) && ...); That's nicer, though strcmp is what the replaced code used to do in patches 2 and 3. Note that memcmp requires the caller to use "KVMKVMKVM\0\0" as the signature (or alternatively hypervisor_cpuid_base can copy the argument into another 12-byte local variable). Paolo -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Tue, Jul 23, 2013 at 05:41:02PM +0800, Jason Wang wrote: > This patch introduce hypervisor_cpuid_base() which loop test the hypervisor > existence function until the signature match and check the number of leaves if > required. This could be used by Xen/KVM guest to detect the existence of > hypervisor. > Looks good to me. Since this touches common code, kvm and xen I expect this to be taken via the tip tree, correct? > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Ingo Molnar <mingo@redhat.com> > Cc: "H. Peter Anvin" <hpa@zytor.com> > Cc: "Paolo Bonzini" <pbonzini@redhat.com> > Cc: Gleb Natapov <gleb@redhat.com> > Cc: x86@kernel.org > Signed-off-by: Jason Wang <jasowang@redhat.com> > --- > arch/x86/include/asm/processor.h | 20 ++++++++++++++++++++ > 1 files changed, 20 insertions(+), 0 deletions(-) > > diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h > index 24cf5ae..a8136d0 100644 > --- a/arch/x86/include/asm/processor.h > +++ b/arch/x86/include/asm/processor.h > @@ -971,6 +971,26 @@ unsigned long calc_aperfmperf_ratio(struct aperfmperf *old, > return ratio; > } > > +static inline uint32_t hypervisor_cpuid_base(const char *sig, uint32_t leaves) > +{ > + uint32_t base, eax, ebx, ecx, edx; > + char signature[13]; > + > + for (base = 0x40000000; base < 0x40010000; base += 0x100) { > + cpuid(base, &eax, &ebx, &ecx, &edx); > + *(uint32_t *)(signature + 0) = ebx; > + *(uint32_t *)(signature + 4) = ecx; > + *(uint32_t *)(signature + 8) = edx; > + signature[12] = 0; > + > + if (!strcmp(sig, signature) && > + (leaves == 0 || ((eax - base) >= leaves))) > + return base; > + } > + > + return 0; > +} > + > extern unsigned long arch_align_stack(unsigned long sp); > extern void free_init_pages(char *what, unsigned long begin, unsigned long end); > > -- > 1.7.1 -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 07/23/2013 04:16 AM, Paolo Bonzini wrote: > > That's nicer, though strcmp is what the replaced code used to do in > patches 2 and 3. > > Note that memcmp requires the caller to use "KVMKVMKVM\0\0" as the > signature (or alternatively hypervisor_cpuid_base can copy the argument > into another 12-byte local variable). > Which is the actual signature, though... -hpa -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 07/23/2013 09:48 PM, Gleb Natapov wrote: > On Tue, Jul 23, 2013 at 05:41:02PM +0800, Jason Wang wrote: >> > This patch introduce hypervisor_cpuid_base() which loop test the hypervisor >> > existence function until the signature match and check the number of leaves if >> > required. This could be used by Xen/KVM guest to detect the existence of >> > hypervisor. >> > > Looks good to me. > > Since this touches common code, kvm and xen I expect this to be taken > via the tip tree, correct? > Yes, I think so. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 07/24/2013 12:03 AM, H. Peter Anvin wrote: > On 07/23/2013 04:16 AM, Paolo Bonzini wrote: >> That's nicer, though strcmp is what the replaced code used to do in >> patches 2 and 3. >> >> Note that memcmp requires the caller to use "KVMKVMKVM\0\0" as the >> signature (or alternatively hypervisor_cpuid_base can copy the argument >> into another 12-byte local variable). >> > Which is the actual signature, though... > > -hpa > > Since it's just a minor optimization. How about just keep using the strcmp()? -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 07/23/2013 09:44 PM, Jason Wang wrote: > > Since it's just a minor optimization. How about just keep using the > strcmp()? > It's more that it enables the rest of the cleanup, making the code easier to read. -hpa -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h index 24cf5ae..a8136d0 100644 --- a/arch/x86/include/asm/processor.h +++ b/arch/x86/include/asm/processor.h @@ -971,6 +971,26 @@ unsigned long calc_aperfmperf_ratio(struct aperfmperf *old, return ratio; } +static inline uint32_t hypervisor_cpuid_base(const char *sig, uint32_t leaves) +{ + uint32_t base, eax, ebx, ecx, edx; + char signature[13]; + + for (base = 0x40000000; base < 0x40010000; base += 0x100) { + cpuid(base, &eax, &ebx, &ecx, &edx); + *(uint32_t *)(signature + 0) = ebx; + *(uint32_t *)(signature + 4) = ecx; + *(uint32_t *)(signature + 8) = edx; + signature[12] = 0; + + if (!strcmp(sig, signature) && + (leaves == 0 || ((eax - base) >= leaves))) + return base; + } + + return 0; +} + extern unsigned long arch_align_stack(unsigned long sp); extern void free_init_pages(char *what, unsigned long begin, unsigned long end);
This patch introduce hypervisor_cpuid_base() which loop test the hypervisor existence function until the signature match and check the number of leaves if required. This could be used by Xen/KVM guest to detect the existence of hypervisor. Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: "Paolo Bonzini" <pbonzini@redhat.com> Cc: Gleb Natapov <gleb@redhat.com> Cc: x86@kernel.org Signed-off-by: Jason Wang <jasowang@redhat.com> --- arch/x86/include/asm/processor.h | 20 ++++++++++++++++++++ 1 files changed, 20 insertions(+), 0 deletions(-)