On Wed, Jun 29, 2022, Paul Durrant wrote: > diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h > index 88a3026ee163..abb0a39f60eb 100644 > --- a/arch/x86/include/asm/kvm_host.h > +++ b/arch/x86/include/asm/kvm_host.h > @@ -638,6 +638,7 @@ struct kvm_vcpu_xen { > struct hrtimer timer; > int poll_evtchn; > struct timer_list poll_timer; > + u32 cpuid_tsc_info; I would prefer to follow vcpu->arch.kvm_cpuid_base and capture the base CPUID function. I have a hard time believing this will be the only case where KVM needs to query XEN CPUID leafs. And cpuid_tsc_info is a confusing name given the helper kvm_xen_setup_tsc_info(); it's odd to see a "setup" helper immediately consume a variable with the same name. It'll incur another CPUID lookup in the update path to check the limit, but again that should be a rare operation so it doesn't seem too onerous. > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > index 031678eff28e..29ed665c51db 100644 > --- a/arch/x86/kvm/x86.c > +++ b/arch/x86/kvm/x86.c > @@ -3110,6 +3110,7 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) > &vcpu->hv_clock.tsc_shift, > &vcpu->hv_clock.tsc_to_system_mul); > vcpu->hw_tsc_khz = tgt_tsc_khz; > + kvm_xen_setup_tsc_info(v); Any objection to s/setup/update? KVM Xen uses "setup" for things like configuring the event channel using userspace input, whereas this is purely updating existing data structures. > } > > vcpu->hv_clock.tsc_timestamp = tsc_timestamp; > diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c > index 610beba35907..c84424d5c8b6 100644 > --- a/arch/x86/kvm/xen.c > +++ b/arch/x86/kvm/xen.c > @@ -10,6 +10,9 @@ > #include "xen.h" > #include "hyperv.h" > #include "lapic.h" > +#include "cpuid.h" > + > +#include <asm/xen/cpuid.h> > > #include <linux/eventfd.h> > #include <linux/kvm_host.h> > @@ -1855,3 +1858,51 @@ void kvm_xen_destroy_vm(struct kvm *kvm) > if (kvm->arch.xen_hvm_config.msr) > static_branch_slow_dec_deferred(&kvm_xen_enabled); > } > + > +void kvm_xen_after_set_cpuid(struct kvm_vcpu *vcpu) > +{ > + u32 base = 0; > + u32 limit; > + u32 function; > + > + vcpu->arch.xen.cpuid_tsc_info = 0; > + > + for_each_possible_hypervisor_cpuid_base(function) { > + struct kvm_cpuid_entry2 *entry = kvm_find_cpuid_entry(vcpu, function, 0); > + > + if (entry && > + entry->ebx == XEN_CPUID_SIGNATURE_EBX && > + entry->ecx == XEN_CPUID_SIGNATURE_ECX && > + entry->edx == XEN_CPUID_SIGNATURE_EDX) { > + base = function; > + limit = entry->eax; > + break; > + } > + } > + if (!base) > + return; Rather than open code a variant of kvm_update_kvm_cpuid_base(), that helper can be tweaked to take a signature. Along with a patch to provide a #define for Xen's signature as a string, this entire function becomes a one-liner. If the below looks ok (won't compile, needs prep patches), I'll test and post a proper mini-series. --- arch/x86/include/asm/kvm_host.h | 1 + arch/x86/kvm/cpuid.c | 2 ++ arch/x86/kvm/x86.c | 1 + arch/x86/kvm/xen.c | 30 ++++++++++++++++++++++++++++++ arch/x86/kvm/xen.h | 22 +++++++++++++++++++++- 5 files changed, 55 insertions(+), 1 deletion(-) diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h index de5a149d0971..b2565d05fc86 100644 --- a/arch/x86/include/asm/kvm_host.h +++ b/arch/x86/include/asm/kvm_host.h @@ -638,6 +638,7 @@ struct kvm_vcpu_xen { struct hrtimer timer; int poll_evtchn; struct timer_list poll_timer; + u32 cpuid_base; }; struct kvm_vcpu_arch { diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c index 0abe3adc9ae3..54ed51799b8d 100644 --- a/arch/x86/kvm/cpuid.c +++ b/arch/x86/kvm/cpuid.c @@ -25,6 +25,7 @@ #include "mmu.h" #include "trace.h" #include "pmu.h" +#include "xen.h" /* * Unlike "struct cpuinfo_x86.x86_capability", kvm_cpu_caps doesn't need to be @@ -309,6 +310,7 @@ static void kvm_vcpu_after_set_cpuid(struct kvm_vcpu *vcpu) __cr4_reserved_bits(guest_cpuid_has, vcpu); kvm_hv_set_cpuid(vcpu); + kvm_xen_after_set_cpuid(vcpu); /* Invoke the vendor callback only after the above state is updated. */ static_call(kvm_x86_vcpu_after_set_cpuid)(vcpu); diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 567d13405445..a624293c66c8 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3110,6 +3110,7 @@ static int kvm_guest_time_update(struct kvm_vcpu *v) &vcpu->hv_clock.tsc_shift, &vcpu->hv_clock.tsc_to_system_mul); vcpu->hw_tsc_khz = tgt_tsc_khz; + kvm_xen_update_tsc_info(v); } vcpu->hv_clock.tsc_timestamp = tsc_timestamp; diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c index 610beba35907..3fc0c194b813 100644 --- a/arch/x86/kvm/xen.c +++ b/arch/x86/kvm/xen.c @@ -10,6 +10,9 @@ #include "xen.h" #include "hyperv.h" #include "lapic.h" +#include "cpuid.h" + +#include <asm/xen/cpuid.h> #include <linux/eventfd.h> #include <linux/kvm_host.h> @@ -1855,3 +1858,30 @@ void kvm_xen_destroy_vm(struct kvm *kvm) if (kvm->arch.xen_hvm_config.msr) static_branch_slow_dec_deferred(&kvm_xen_enabled); } + +void kvm_xen_update_tsc_info(struct kvm_vcpu *vcpu) +{ + struct kvm_cpuid_entry2 *entry; + u32 function; + + if (!vcpu->arch.xen.cpuid_base) + return; + + entry = kvm_find_cpuid_entry(vcpu, vcpu->arch.xen.cpuid_base, 0); + if (WARN_ON_ONCE(!entry)) + return; + + function = vcpu->arch.xen.cpuid_base | XEN_CPUID_LEAF(3); + if (function > entry->eax) + return; + + entry = kvm_find_cpuid_entry(vcpu, function, 1); + if (entry) { + entry->ecx = vcpu->arch.hv_clock.tsc_to_system_mul; + entry->edx = vcpu->arch.hv_clock.tsc_shift; + } + + entry = kvm_find_cpuid_entry(vcpu, function, 2); + if (entry) + entry->eax = vcpu->arch.hw_tsc_khz; +} diff --git a/arch/x86/kvm/xen.h b/arch/x86/kvm/xen.h index 532a535a9e99..b8161b99b82a 100644 --- a/arch/x86/kvm/xen.h +++ b/arch/x86/kvm/xen.h @@ -9,9 +9,14 @@ #ifndef __ARCH_X86_KVM_XEN_H__ #define __ARCH_X86_KVM_XEN_H__ -#ifdef CONFIG_KVM_XEN #include <linux/jump_label_ratelimit.h> +#include <asm/xen/cpuid.h> + +#include "cpuid.h" + +#ifdef CONFIG_KVM_XEN + extern struct static_key_false_deferred kvm_xen_enabled; int __kvm_xen_has_interrupt(struct kvm_vcpu *vcpu); @@ -32,6 +37,13 @@ int kvm_xen_set_evtchn_fast(struct kvm_xen_evtchn *xe, int kvm_xen_setup_evtchn(struct kvm *kvm, struct kvm_kernel_irq_routing_entry *e, const struct kvm_irq_routing_entry *ue); +void kvm_xen_update_tsc_info(struct kvm_vcpu *vcpu); + +static inline void kvm_xen_after_set_cpuid(struct kvm_vcpu *vcpu) +{ + vcpu->arch.xen.cpuid_base = + kvm_get_hypervisor_cpuid_base(vcpu, XEN_CPUID_SIGNATURE); +} static inline bool kvm_xen_msr_enabled(struct kvm *kvm) { @@ -135,6 +147,14 @@ static inline bool kvm_xen_timer_enabled(struct kvm_vcpu *vcpu) { return false; } + +static inline void kvm_xen_after_set_cpuid(struct kvm_vcpu *vcpu) +{ +} + +static inline void kvm_xen_update_tsc_info(struct kvm_vcpu *vcpu) +{ +} #endif int kvm_xen_hypercall(struct kvm_vcpu *vcpu); base-commit: b08b2f54c49d8f96a22107c444d500dff73ec2a6 --