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Message-Id: <20220629130514.15780-1-pdurrant@amazon.com>
Date: Wed, 29 Jun 2022 14:05:13 +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 v5] KVM: x86/xen: Update Xen CPUID Leaf 4 (tsc info) sub-leaves, if present
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@...zon.com>
---
Cc: David Woodhouse <dwmw2@...radead.org>
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/kvm/cpuid.c | 2 ++
arch/x86/kvm/x86.c | 1 +
arch/x86/kvm/xen.c | 51 +++++++++++++++++++++++++++++++++
arch/x86/kvm/xen.h | 10 +++++++
5 files changed, 65 insertions(+)
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;
};
struct kvm_vcpu_arch {
diff --git a/arch/x86/kvm/cpuid.c b/arch/x86/kvm/cpuid.c
index d47222ab8e6e..544d0f823ee5 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_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 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);
}
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;
+
+ function = base | XEN_CPUID_LEAF(3);
+ if (function > limit)
+ return;
+
+ vcpu->arch.xen.cpuid_tsc_info = function;
+}
+
+void kvm_xen_setup_tsc_info(struct kvm_vcpu *vcpu)
+{
+ struct kvm_cpuid_entry2 *entry;
+
+ if (!vcpu->arch.xen.cpuid_tsc_info)
+ return;
+
+ entry = kvm_find_cpuid_entry(vcpu, vcpu->arch.xen.cpuid_tsc_info, 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, vcpu->arch.xen.cpuid_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..b2ca434431d6 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_after_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_after_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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