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    Subject[PATCH v7 2/2] KVM: x86/xen: update Xen CPUID Leaf 4 (tsc info) sub-leaves, if present
    Date
    The scaling information in subleaf 1 should match the values set by KVM in
    the 'vcpu_info' sub-structure 'time_info' (a.k.a. pvclock_vcpu_time_info)
    which is shared with the guest, but is not directly available to the VMM.
    The offset values are not set since a TSC offset is already applied.
    The TSC frequency should also be set in sub-leaf 2.

    Signed-off-by: Paul Durrant <pdurrant@amazon.com>
    ---
    Cc: Sean Christopherson <seanjc@google.com>
    Cc: Paolo Bonzini <pbonzini@redhat.com>
    Cc: Juergen Gross <jgross@suse.com>
    Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Dave Hansen <dave.hansen@linux.intel.com>
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    Cc: David Woodhouse <dwmw2@infradead.org>

    v7:
    - Add a definition of XEN_SIGNATURE into asm/xen/hypervisor.h
    and use that

    v6:
    - Stash Xen cpuid base and limit values when cpuid is set
    - Re-name kvm_xen_setup_tsc_info() to kvm_xen_update_tsc_info()

    v5:
    - Drop the caching of the CPUID entry pointers and only update the
    sub-leaves if the CPU frequency has actually changed

    v4:
    - Update commit comment

    v3:
    - Add leaf limit check in kvm_xen_set_cpuid()

    v2:
    - Make sure sub-leaf pointers are NULLed if the time leaf is removed
    ---
    arch/x86/include/asm/kvm_host.h | 1 +
    arch/x86/include/asm/xen/hypervisor.h | 4 +++-
    arch/x86/kvm/cpuid.c | 2 ++
    arch/x86/kvm/x86.c | 1 +
    arch/x86/kvm/xen.c | 26 ++++++++++++++++++++++++++
    arch/x86/kvm/xen.h | 7 +++++++
    6 files changed, 40 insertions(+), 1 deletion(-)

    diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
    index 85cbe4571ac9..f3e9f6e4b3ea 100644
    --- a/arch/x86/include/asm/kvm_host.h
    +++ b/arch/x86/include/asm/kvm_host.h
    @@ -703,6 +703,7 @@ struct kvm_vcpu_xen {
    struct hrtimer timer;
    int poll_evtchn;
    struct timer_list poll_timer;
    + struct kvm_hypervisor_cpuid cpuid;
    };

    struct kvm_queued_exception {
    diff --git a/arch/x86/include/asm/xen/hypervisor.h b/arch/x86/include/asm/xen/hypervisor.h
    index 16f548a661cf..5fc35f889cd1 100644
    --- a/arch/x86/include/asm/xen/hypervisor.h
    +++ b/arch/x86/include/asm/xen/hypervisor.h
    @@ -38,9 +38,11 @@ extern struct start_info *xen_start_info;

    #include <asm/processor.h>

    +#define XEN_SIGNATURE "XenVMMXenVMM"
    +
    static inline uint32_t xen_cpuid_base(void)
    {
    - return hypervisor_cpuid_base("XenVMMXenVMM", 2);
    + return hypervisor_cpuid_base(XEN_SIGNATURE, 2);
    }

    struct pci_dev;
    diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
    index db5a4d38fcd0..560f880cc9fd 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
    @@ -442,6 +443,7 @@ static int kvm_set_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2,
    vcpu->arch.cpuid_nent = nent;

    vcpu->arch.kvm_cpuid = kvm_get_hypervisor_cpuid(vcpu, KVM_SIGNATURE);
    + vcpu->arch.xen.cpuid = kvm_get_hypervisor_cpuid(vcpu, XEN_SIGNATURE);
    kvm_vcpu_after_set_cpuid(vcpu);

    return 0;
    diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
    index f6ef44dc8a0e..e849a5445cac 100644
    --- a/arch/x86/kvm/x86.c
    +++ b/arch/x86/kvm/x86.c
    @@ -3158,6 +3158,7 @@ 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 2e29bdc2949c..fbfc7c17defd 100644
    --- a/arch/x86/kvm/xen.c
    +++ b/arch/x86/kvm/xen.c
    @@ -22,6 +22,9 @@
    #include <xen/interface/event_channel.h>
    #include <xen/interface/sched.h>

    +#include <asm/xen/cpuid.h>
    +
    +#include "cpuid.h"
    #include "trace.h"

    static int kvm_xen_set_evtchn(struct kvm_xen_evtchn *xe, struct kvm *kvm);
    @@ -2067,6 +2070,29 @@ void kvm_xen_destroy_vcpu(struct kvm_vcpu *vcpu)
    del_timer_sync(&vcpu->arch.xen.poll_timer);
    }

    +void kvm_xen_update_tsc_info(struct kvm_vcpu *vcpu)
    +{
    + struct kvm_cpuid_entry2 *entry;
    + u32 function;
    +
    + if (!vcpu->arch.xen.cpuid.base)
    + return;
    +
    + function = vcpu->arch.xen.cpuid.base | XEN_CPUID_LEAF(3);
    + if (function > vcpu->arch.xen.cpuid.limit)
    + return;
    +
    + entry = kvm_find_cpuid_entry_index(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_index(vcpu, function, 2);
    + if (entry)
    + entry->eax = vcpu->arch.hw_tsc_khz;
    +}
    +
    void kvm_xen_init_vm(struct kvm *kvm)
    {
    idr_init(&kvm->arch.xen.evtchn_ports);
    diff --git a/arch/x86/kvm/xen.h b/arch/x86/kvm/xen.h
    index ea33d80a0c51..f8f1fe22d090 100644
    --- a/arch/x86/kvm/xen.h
    +++ b/arch/x86/kvm/xen.h
    @@ -9,6 +9,8 @@
    #ifndef __ARCH_X86_KVM_XEN_H__
    #define __ARCH_X86_KVM_XEN_H__

    +#include <asm/xen/hypervisor.h>
    +
    #ifdef CONFIG_KVM_XEN
    #include <linux/jump_label_ratelimit.h>

    @@ -32,6 +34,7 @@ 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 bool kvm_xen_msr_enabled(struct kvm *kvm)
    {
    @@ -135,6 +138,10 @@ static inline bool kvm_xen_timer_enabled(struct kvm_vcpu *vcpu)
    {
    return false;
    }
    +
    +static inline void kvm_xen_update_tsc_info(struct kvm_vcpu *vcpu)
    +{
    +}
    #endif

    int kvm_xen_hypercall(struct kvm_vcpu *vcpu);
    --
    2.20.1
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