lkml.org 
[lkml]   [2021]   [Jul]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH AUTOSEL 5.13 68/85] KVM: arm64: Restore PMU configuration on first run
Date
From: Marc Zyngier <maz@kernel.org>

[ Upstream commit d0c94c49792cf780cbfefe29f81bb8c3b73bc76b ]

Restoring a guest with an active virtual PMU results in no perf
counters being instanciated on the host side. Not quite what
you'd expect from a restore.

In order to fix this, force a writeback of PMCR_EL0 on the first
run of a vcpu (using a new request so that it happens once the
vcpu has been loaded). This will in turn create all the host-side
counters that were missing.

Reported-by: Jinank Jain <jinankj@amazon.de>
Tested-by: Jinank Jain <jinankj@amazon.de>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/87wnrbylxv.wl-maz@kernel.org
Link: https://lore.kernel.org/r/b53dfcf9bbc4db7f96154b1cd5188d72b9766358.camel@amazon.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/arm64/include/asm/kvm_host.h | 1 +
arch/arm64/kvm/arm.c | 4 ++++
arch/arm64/kvm/pmu-emul.c | 3 +++
3 files changed, 8 insertions(+)

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 7cd7d5c8c4bc..6336b4309114 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -46,6 +46,7 @@
#define KVM_REQ_VCPU_RESET KVM_ARCH_REQ(2)
#define KVM_REQ_RECORD_STEAL KVM_ARCH_REQ(3)
#define KVM_REQ_RELOAD_GICv4 KVM_ARCH_REQ(4)
+#define KVM_REQ_RELOAD_PMU KVM_ARCH_REQ(5)

#define KVM_DIRTY_LOG_MANUAL_CAPS (KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE | \
KVM_DIRTY_LOG_INITIALLY_SET)
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index e720148232a0..facf4d41d32a 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -689,6 +689,10 @@ static void check_vcpu_requests(struct kvm_vcpu *vcpu)
vgic_v4_load(vcpu);
preempt_enable();
}
+
+ if (kvm_check_request(KVM_REQ_RELOAD_PMU, vcpu))
+ kvm_pmu_handle_pmcr(vcpu,
+ __vcpu_sys_reg(vcpu, PMCR_EL0));
}
}

diff --git a/arch/arm64/kvm/pmu-emul.c b/arch/arm64/kvm/pmu-emul.c
index fd167d4f4215..a0bbb7111f57 100644
--- a/arch/arm64/kvm/pmu-emul.c
+++ b/arch/arm64/kvm/pmu-emul.c
@@ -850,6 +850,9 @@ int kvm_arm_pmu_v3_enable(struct kvm_vcpu *vcpu)
return -EINVAL;
}

+ /* One-off reload of the PMU on first run */
+ kvm_make_request(KVM_REQ_RELOAD_PMU, vcpu);
+
return 0;
}

--
2.30.2
\
 
 \ /
  Last update: 2021-07-05 01:10    [W:0.271 / U:0.988 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site