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Message-Id: <20220622143306.13248-1-pdurrant@amazon.com>
Date: Wed, 22 Jun 2022 15:33:06 +0100
From: Paul Durrant <pdurrant@...zon.com>
To: x86@...nel.org, kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc: Paul Durrant <pdurrant@...zon.com>,
David Woodhouse <dwmw2@...radead.org>,
Paolo Bonzini <pbonzini@...hat.com>,
Sean Christopherson <seanjc@...gle.com>,
Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
Joerg Roedel <joro@...tes.org>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
Dave Hansen <dave.hansen@...ux.intel.com>,
"H. Peter Anvin" <hpa@...or.com>
Subject: [PATCH v3] KVM: x86/xen: Update Xen CPUID Leaf 4 (tsc info) sub-leaves, if present
The scaling information in sub-leaf 1 should match the values in the
'vcpu_info' sub-structure 'time_info' (a.k.a. pvclock_vcpu_time_info) which
is shared with the guest. The offset values are not set since a TSC offset
is already applied.
The host TSC frequency should also be set in sub-leaf 2.
This patch adds a new kvm_xen_set_cpuid() function that scans for the
relevant CPUID leaf when the CPUID information is updated by the VMM and
stashes pointers to the sub-leaves in the kvm_vcpu_xen structure.
The values are then updated by a call to the, also new,
kvm_xen_setup_tsc_info() function made at the end of
kvm_guest_time_update() just before entering the guest.
Signed-off-by: Paul Durrant <pdurrant@...zon.com>
---
Cc: David Woodhouse <dwmw2@...radead.org>
v2:
- Make sure sub-leaf pointers are NULLed if the time leaf is removed
v3:
- Add leaf limit check in kvm_xen_set_cpuid()
---
arch/x86/include/asm/kvm_host.h | 2 ++
arch/x86/kvm/cpuid.c | 2 ++
arch/x86/kvm/x86.c | 1 +
arch/x86/kvm/xen.c | 49 +++++++++++++++++++++++++++++++++
arch/x86/kvm/xen.h | 10 +++++++
5 files changed, 64 insertions(+)
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 1038ccb7056a..f77a4940542f 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -638,6 +638,8 @@ struct kvm_vcpu_xen {
struct hrtimer timer;
int poll_evtchn;
struct timer_list poll_timer;
+ struct kvm_cpuid_entry2 *tsc_info_1;
+ struct kvm_cpuid_entry2 *tsc_info_2;
};
struct kvm_vcpu_arch {
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index d47222ab8e6e..eb6cd88c974a 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
@@ -310,6 +311,7 @@ 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_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 00e23dc518e0..8b45f9975e45 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -3123,6 +3123,7 @@ static int kvm_guest_time_update(struct kvm_vcpu *v)
if (vcpu->xen.vcpu_time_info_cache.active)
kvm_setup_guest_pvclock(v, &vcpu->xen.vcpu_time_info_cache, 0);
kvm_hv_setup_tsc_page(v->kvm, &vcpu->hv_clock);
+ kvm_xen_setup_tsc_info(v);
return 0;
}
diff --git a/arch/x86/kvm/xen.c b/arch/x86/kvm/xen.c
index 610beba35907..08e65ec6c793 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 +1858,49 @@ 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_set_cpuid(struct kvm_vcpu *vcpu)
+{
+ u32 base = 0;
+ u32 limit;
+ u32 function;
+
+ vcpu->arch.xen.tsc_info_1 = NULL;
+ vcpu->arch.xen.tsc_info_2 = NULL;
+
+ 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;
+
+ function = base | XEN_CPUID_LEAF(3);
+ if (function > limit)
+ return;
+
+ vcpu->arch.xen.tsc_info_1 = kvm_find_cpuid_entry(vcpu, function, 1);
+ vcpu->arch.xen.tsc_info_2 = kvm_find_cpuid_entry(vcpu, function, 2);
+}
+
+void kvm_xen_setup_tsc_info(struct kvm_vcpu *vcpu)
+{
+ struct kvm_cpuid_entry2 *entry = vcpu->arch.xen.tsc_info_1;
+
+ if (entry) {
+ entry->ecx = vcpu->arch.hv_clock.tsc_to_system_mul;
+ entry->edx = vcpu->arch.hv_clock.tsc_shift;
+ }
+
+ entry = vcpu->arch.xen.tsc_info_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..1afb663318a9 100644
--- a/arch/x86/kvm/xen.h
+++ b/arch/x86/kvm/xen.h
@@ -32,6 +32,8 @@ 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_set_cpuid(struct kvm_vcpu *vcpu);
+void kvm_xen_setup_tsc_info(struct kvm_vcpu *vcpu);
static inline bool kvm_xen_msr_enabled(struct kvm *kvm)
{
@@ -135,6 +137,14 @@ static inline bool kvm_xen_timer_enabled(struct kvm_vcpu *vcpu)
{
return false;
}
+
+static inline void kvm_xen_set_cpuid(struct kvm_vcpu *vcpu)
+{
+}
+
+static inline void kvm_xen_setup_tsc_info(struct kvm_vcpu *vcpu)
+{
+}
#endif
int kvm_xen_hypercall(struct kvm_vcpu *vcpu);
--
2.20.1
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