This is a note to let you know that I've just added the patch titled
KVM: x86: Register perf callbacks after calling vendor's hardware_setup()
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-x86-register-perf-callbacks-after-calling-vendor-s-hardware_setup.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 5c7df80e2ce4c954c80eb4ecf5fa002a5ff5d2d6 Mon Sep 17 00:00:00 2001
From: Sean Christopherson <seanjc@xxxxxxxxxx>
Date: Thu, 11 Nov 2021 02:07:23 +0000
Subject: KVM: x86: Register perf callbacks after calling vendor's hardware_setup()
From: Sean Christopherson <seanjc@xxxxxxxxxx>
commit 5c7df80e2ce4c954c80eb4ecf5fa002a5ff5d2d6 upstream.
Wait to register perf callbacks until after doing vendor hardaware setup.
VMX's hardware_setup() configures Intel Processor Trace (PT) mode, and a
future fix to register the Intel PT guest interrupt hook if and only if
Intel PT is exposed to the guest will consume the configured PT mode.
Delaying registration to hardware setup is effectively a nop as KVM's perf
hooks all pivot on the per-CPU current_vcpu, which is non-NULL only when
KVM is handling an IRQ/NMI in a VM-Exit path. I.e. current_vcpu will be
NULL throughout both kvm_arch_init() and kvm_arch_hardware_setup().
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Link: https://lore.kernel.org/r/20211111020738.2512932-3-seanjc@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/kvm/x86.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -8551,8 +8551,6 @@ int kvm_arch_init(void *opaque)
kvm_timer_init();
- perf_register_guest_info_callbacks(&kvm_guest_cbs);
-
if (boot_cpu_has(X86_FEATURE_XSAVE)) {
host_xcr0 = xgetbv(XCR_XFEATURE_ENABLED_MASK);
supported_xcr0 = host_xcr0 & KVM_SUPPORTED_XCR0;
@@ -8586,7 +8584,6 @@ void kvm_arch_exit(void)
clear_hv_tscchange_cb();
#endif
kvm_lapic_exit();
- perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
if (!boot_cpu_has(X86_FEATURE_CONSTANT_TSC))
cpufreq_unregister_notifier(&kvmclock_cpufreq_notifier_block,
@@ -11186,6 +11183,8 @@ int kvm_arch_hardware_setup(void *opaque
memcpy(&kvm_x86_ops, ops->runtime_ops, sizeof(kvm_x86_ops));
kvm_ops_static_call_update();
+ perf_register_guest_info_callbacks(&kvm_guest_cbs);
+
if (!kvm_cpu_cap_has(X86_FEATURE_XSAVES))
supported_xss = 0;
@@ -11213,6 +11212,8 @@ int kvm_arch_hardware_setup(void *opaque
void kvm_arch_hardware_unsetup(void)
{
+ perf_unregister_guest_info_callbacks(&kvm_guest_cbs);
+
static_call(kvm_x86_hardware_unsetup)();
}
Patches currently in stable-queue which might be from seanjc@xxxxxxxxxx are
queue-5.15/kvm-x86-register-processor-trace-interrupt-hook-iff-pt-enabled-in-guest.patch
queue-5.15/perf-protect-perf_guest_cbs-with-rcu.patch
queue-5.15/kvm-x86-register-perf-callbacks-after-calling-vendor-s-hardware_setup.patch
