KVM ARM Archive on lore.kernel.org
 help / color / Atom feed
From: Marc Zyngier <maz@kernel.org>
To: linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Cc: Will Deacon <will@kernel.org>
Subject: [PATCH v3 3/4] KVM: arm64: pmu: Set the CHAINED attribute before creating the in-kernel event
Date: Fri, 11 Oct 2019 13:39:53 +0100
Message-ID: <20191011123954.31378-4-maz@kernel.org> (raw)
In-Reply-To: <20191011123954.31378-1-maz@kernel.org>

The current convention for KVM to request a chained event from the
host PMU is to set bit[0] in attr.config1 (PERF_ATTR_CFG1_KVM_PMU_CHAINED).

But as it turns out, this bit gets set *after* we create the kernel
event that backs our virtual counter, meaning that we never get
a 64bit counter.

Moving the setting to an earlier point solves the problem.

Fixes: 80f393a23be6 ("KVM: arm/arm64: Support chained PMU counters")
Signed-off-by: Marc Zyngier <maz@kernel.org>
 virt/kvm/arm/pmu.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/virt/kvm/arm/pmu.c b/virt/kvm/arm/pmu.c
index c30c3a74fc7f..f291d4ac3519 100644
--- a/virt/kvm/arm/pmu.c
+++ b/virt/kvm/arm/pmu.c
@@ -569,12 +569,12 @@ static void kvm_pmu_create_perf_event(struct kvm_vcpu *vcpu, u64 select_idx)
 		 * high counter.
 		attr.sample_period = (-counter) & GENMASK(63, 0);
+		if (kvm_pmu_counter_is_enabled(vcpu, pmc->idx + 1))
+			attr.config1 |= PERF_ATTR_CFG1_KVM_PMU_CHAINED;
 		event = perf_event_create_kernel_counter(&attr, -1, current,
 							 pmc + 1);
-		if (kvm_pmu_counter_is_enabled(vcpu, pmc->idx + 1))
-			attr.config1 |= PERF_ATTR_CFG1_KVM_PMU_CHAINED;
 	} else {
 		/* The initial sample period (overflow count) of an event. */
 		if (kvm_pmu_idx_is_64bit(vcpu, pmc->idx))

kvmarm mailing list

  parent reply index

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-10-11 12:39 [PATCH v3 0/4] KVM: arm64: Assorted PMU emulation fixes Marc Zyngier
2019-10-11 12:39 ` [PATCH v3 1/4] KVM: arm64: pmu: Fix cycle counter truncation Marc Zyngier
2019-10-11 12:39 ` [PATCH v3 2/4] arm64: KVM: Handle PMCR_EL0.LC as RES1 on pure AArch64 systems Marc Zyngier
2019-10-11 12:39 ` Marc Zyngier [this message]
2019-10-11 14:19   ` [PATCH v3 3/4] KVM: arm64: pmu: Set the CHAINED attribute before creating the in-kernel event Andrew Murray
2019-10-11 12:39 ` [PATCH v3 4/4] KVM: arm64: pmu: Reset sample period on overflow handling Marc Zyngier
2019-10-15 10:00   ` Andrew Murray

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20191011123954.31378-4-maz@kernel.org \
    --to=maz@kernel.org \
    --cc=kvm@vger.kernel.org \
    --cc=kvmarm@lists.cs.columbia.edu \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=will@kernel.org \


* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

KVM ARM Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/kvmarm/0 kvmarm/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 kvmarm kvmarm/ https://lore.kernel.org/kvmarm \
		kvmarm@lists.cs.columbia.edu kvmarm@archiver.kernel.org
	public-inbox-index kvmarm

Example config snippet for mirrors

Newsgroup available over NNTP:

AGPL code for this site: git clone https://public-inbox.org/ public-inbox