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Subject[PATCH v6 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: 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>

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 | 11 ++++++-----
arch/x86/kvm/cpuid.c | 2 ++
arch/x86/kvm/x86.c | 1 +
arch/x86/kvm/xen.c | 26 ++++++++++++++++++++++++++
arch/x86/kvm/xen.h | 7 +++++++
5 files changed, 42 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index ff201ad35551..44329594bdf7 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -678,6 +678,11 @@ struct kvm_vcpu_hv {
} nested;
};

+struct kvm_hypervisor_cpuid {
+ u32 base;
+ u32 limit;
+};
+
/* Xen HVM per vcpu emulation context */
struct kvm_vcpu_xen {
u64 hypercall_rip;
@@ -698,6 +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 {
@@ -710,11 +716,6 @@ struct kvm_queued_exception {
bool has_payload;
};

-struct kvm_hypervisor_cpuid {
- u32 base;
- u32 limit;
-};
-
struct kvm_vcpu_arch {
/*
* rip and regs accesses must go through
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index 2468720f8d84..e661413ddf8d 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
@@ -441,6 +442,7 @@ static int kvm_set_cpuid(struct kvm_vcpu *vcpu, struct kvm_cpuid_entry2 *e2,
vcpu->arch.cpuid_nent = nent;

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

return 0;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index fd6c01a39312..60acc55f0c00 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 d7af40240248..46297521791c 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);
@@ -2061,6 +2064,29 @@ 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..88dd085e10f8 100644
--- a/arch/x86/kvm/xen.h
+++ b/arch/x86/kvm/xen.h
@@ -32,6 +32,7 @@ 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 +136,10 @@ 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);
@@ -143,6 +148,8 @@ int kvm_xen_hypercall(struct kvm_vcpu *vcpu);
#include <asm/xen/interface.h>
#include <xen/interface/vcpu.h>

+#define XEN_SIGNATURE "XenVMMXenVMM"
+
void kvm_xen_update_runstate(struct kvm_vcpu *vcpu, int state);

static inline void kvm_xen_runstate_set_running(struct kvm_vcpu *vcpu)
--
2.20.1
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