From: Punit Agrawal <punit.agrawal@arm.com>
To: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Cc: Punit Agrawal <punit.agrawal@arm.com>,
Christoffer Dall <christoffer.dall@linaro.org>,
Marc Zyngier <marc.zyngier@arm.com>,
Steven Rostedt <rostedt@goodmis.org>,
Ingo Molnar <mingo@redhat.com>, Will Deacon <will.deacon@arm.com>
Subject: [RFC PATCH 7/7] arm64: KVM: Enable selective trapping of TLB instructions
Date: Tue, 16 Aug 2016 11:45:12 +0100 [thread overview]
Message-ID: <1471344312-26685-8-git-send-email-punit.agrawal@arm.com> (raw)
In-Reply-To: <1471344312-26685-1-git-send-email-punit.agrawal@arm.com>
The TTLB bit of Hypervisor Control Register (HCR_EL2) controls the
trapping of guest TLB maintenance instructions. Taking the trap requires
a switch to the hypervisor and is an expensive operation.
Enable selective trapping of guest TLB instructions when the associated
perf trace event is enabled for a specific virtual machine.
Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Cc: Christoffer Dall <christoffer.dall@linaro.org>
Cc: Marc Zyngier <marc.zyngier@arm.com>
---
arch/arm64/kvm/perf_trace.c | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)
diff --git a/arch/arm64/kvm/perf_trace.c b/arch/arm64/kvm/perf_trace.c
index 8bacd18..f26da1d 100644
--- a/arch/arm64/kvm/perf_trace.c
+++ b/arch/arm64/kvm/perf_trace.c
@@ -17,6 +17,8 @@
#include <linux/kvm_host.h>
#include <linux/trace_events.h>
+#include <asm/kvm_emulate.h>
+
typedef int (*perf_trace_callback_fn)(struct kvm *kvm, bool enable);
struct kvm_trace_hook {
@@ -24,7 +26,37 @@ struct kvm_trace_hook {
perf_trace_callback_fn setup_fn;
};
+static int tlb_invalidate_trap(struct kvm *kvm, bool enable)
+{
+ int i;
+ struct kvm_vcpu *vcpu;
+
+ /*
+ * Halt the VM to ensure atomic update across all vcpus (this
+ * avoids racy behaviour against other modifications of
+ * HCR_EL2 such as kvm_toggle_cache/kvm_set_way_flush).
+ */
+ kvm_arm_halt_guest(kvm);
+ kvm_for_each_vcpu(i, vcpu, kvm) {
+ unsigned long hcr = vcpu_get_hcr(vcpu);
+
+ if (enable)
+ hcr |= HCR_TTLB;
+ else
+ hcr &= ~HCR_TTLB;
+
+ vcpu_set_hcr(vcpu, hcr);
+ }
+ kvm_arm_resume_guest(kvm);
+
+ return 0;
+}
+
static struct kvm_trace_hook trace_hook[] = {
+ {
+ .key = "kvm_tlb_invalidate",
+ .setup_fn = tlb_invalidate_trap,
+ },
{ },
};
--
2.8.1
next prev parent reply other threads:[~2016-08-16 10:47 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-16 10:45 [RFC PATCH 0/7] Add support for monitoring guest TLB operations Punit Agrawal
2016-08-16 10:45 ` [RFC PATCH 1/7] perf/trace: Add notification for perf trace events Punit Agrawal
2016-08-31 11:01 ` Punit Agrawal
2016-08-16 10:45 ` [RFC PATCH 2/7] KVM: Track the pid of the VM process Punit Agrawal
2016-08-16 10:45 ` [RFC PATCH 3/7] KVM: arm/arm64: Register perf trace event notifier Punit Agrawal
2016-08-16 10:45 ` [RFC PATCH 4/7] arm64: tlbflush.h: add __tlbi() macro Punit Agrawal
2016-08-19 13:24 ` Will Deacon
2016-08-19 13:34 ` Punit Agrawal
2016-08-16 10:45 ` [RFC PATCH 5/7] arm64/kvm: hyp: tlb: use __tlbi() helper Punit Agrawal
2016-08-16 10:45 ` [RFC PATCH 6/7] arm64: KVM: Handle trappable TLB instructions Punit Agrawal
2016-08-19 15:18 ` Will Deacon
2016-08-24 10:40 ` Punit Agrawal
2016-08-26 9:37 ` Punit Agrawal
2016-08-26 12:21 ` Marc Zyngier
2016-09-01 14:55 ` Will Deacon
2016-09-01 18:29 ` Punit Agrawal
2016-08-16 10:45 ` Punit Agrawal [this message]
2016-08-17 15:58 ` [RFC PATCH 0/7] Add support for monitoring guest TLB operations Paolo Bonzini
2016-08-17 17:01 ` Punit Agrawal
2016-08-17 17:02 ` Paolo Bonzini
2016-08-17 17:20 ` Punit Agrawal
2016-08-18 7:04 ` Paolo Bonzini
Reply instructions:
You may reply publicly 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:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1471344312-26685-8-git-send-email-punit.agrawal@arm.com \
--to=punit.agrawal@arm.com \
--cc=christoffer.dall@linaro.org \
--cc=kvm@vger.kernel.org \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=marc.zyngier@arm.com \
--cc=mingo@redhat.com \
--cc=rostedt@goodmis.org \
--cc=will.deacon@arm.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).