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.
Cache pointers to the sub-leaves when CPUID is updated by the VMM and
populate the relevant information prior to entering the guest.
Signed-off-by: Paul Durrant <[email protected]>
---
Cc: David Woodhouse <[email protected]>
v2:
- Make sure sub-leaf pointers are NULLed if the time leaf is removed
v3:
- Add leaf limit check in kvm_xen_set_cpuid()
v4:
- Update commit comment
---
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
On Wed, Jun 22, 2022, Paul Durrant wrote:
> 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.
>
> Cache pointers to the sub-leaves when CPUID is updated by the VMM and
> populate the relevant information prior to entering the guest.
All of my comments about the code still apply.
https://lore.kernel.org/all/[email protected]
> Signed-off-by: Paul Durrant <[email protected]>
> ---
> Cc: David Woodhouse <[email protected]>
Cc: can go in the changelog, it's helpful info to carry with the commit as it
documents who was made aware of the patch, e.g. show who may have had a cance to
object/review.
>
> v2:
> - Make sure sub-leaf pointers are NULLed if the time leaf is removed
>
> v3:
> - Add leaf limit check in kvm_xen_set_cpuid()
>
> v4:
> - Update commit comment
Please start with the most recent verison and work backardwards, that way reviewers
can quickly see the delta for _this_ version. I.e.
v4:
v3:
v2:
v1:
> -----Original Message-----
> From: Sean Christopherson <[email protected]>
> Sent: 27 June 2022 16:19
> To: Durrant, Paul <[email protected]>
> Cc: [email protected]; [email protected]; [email protected]; David Woodhouse
> <[email protected]>; Paolo Bonzini <[email protected]>; Vitaly Kuznetsov <[email protected]>;
> Wanpeng Li <[email protected]>; Jim Mattson <[email protected]>; Joerg Roedel <[email protected]>;
> Thomas Gleixner <[email protected]>; Ingo Molnar <[email protected]>; Borislav Petkov <[email protected]>;
> Dave Hansen <[email protected]>; H. Peter Anvin <[email protected]>
> Subject: RE: [EXTERNAL][PATCH v4] KVM: x86/xen: Update Xen CPUID Leaf 4 (tsc info) sub-leaves, if
> present
>
> CAUTION: This email originated from outside of the organization. Do not click links or open
> attachments unless you can confirm the sender and know the content is safe.
>
>
>
> On Wed, Jun 22, 2022, Paul Durrant wrote:
> > 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.
> >
> > Cache pointers to the sub-leaves when CPUID is updated by the VMM and
> > populate the relevant information prior to entering the guest.
>
> All of my comments about the code still apply.
>
> https://lore.kernel.org/all/[email protected]
>
Apologies. Not sure how I missed them; I'll send a response shortly.
> > Signed-off-by: Paul Durrant <[email protected]>
> > ---
> > Cc: David Woodhouse <[email protected]>
>
> Cc: can go in the changelog, it's helpful info to carry with the commit as it
> documents who was made aware of the patch, e.g. show who may have had a cance to
> object/review.
>
> >
> > v2:
> > - Make sure sub-leaf pointers are NULLed if the time leaf is removed
> >
> > v3:
> > - Add leaf limit check in kvm_xen_set_cpuid()
> >
> > v4:
> > - Update commit comment
>
> Please start with the most recent verison and work backardwards, that way reviewers
> can quickly see the delta for _this_ version. I.e.
>
>
> v4:
>
> v3:
>
> v2:
>
> v1:
Ok.
Paul