linux-kernel - Re: [PATCH v7 00/10] arm64: Stolen time support

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Message-ID: <5b3968d8-9a5a-ee9d-70b3-436dc052dd0a@arm.com>
Date:   Wed, 23 Oct 2019 14:50:14 +0100
From:   Steven Price <steven.price@....com>
To:     Marc Zyngier <maz@...nel.org>
Cc:     Mark Rutland <mark.rutland@....com>, kvm@...r.kernel.org,
        Radim Krčmář <rkrcmar@...hat.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Suzuki K Pouloze <suzuki.poulose@....com>,
        linux-doc@...r.kernel.org, Russell King <linux@...linux.org.uk>,
        linux-kernel@...r.kernel.org, James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Will Deacon <will@...nel.org>, kvmarm@...ts.cs.columbia.edu,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v7 00/10] arm64: Stolen time support

On 23/10/2019 13:39, Marc Zyngier wrote:
> Hi Steven,
> 
> On 2019-10-21 16:28, Steven Price wrote:
>> This series add support for paravirtualized time for arm64 guests and
>> KVM hosts following the specification in Arm's document DEN 0057A:
>>
>> https://developer.arm.com/docs/den0057/a
>>
>> It implements support for stolen time, allowing the guest to
>> identify time when it is forcibly not executing.
>>
>> Note that Live Physical Time (LPT) which was previously part of the
>> above specification has now been removed.
>>
>> Also available as a git tree:
>> git://linux-arm.org/linux-sp.git stolen_time/v7
> 
> Can you please point me to userspace patches that I could apply to
> kvmtool? I'd like to give this series a go as part of my normal testing.

I don't have a proper patch yet, but the below is what I've been testing
with (this breaks with kernels without PV-time).

Steve

----8<----
>From 8f6540cfbe2842f3ee422c07fbd1f590534cc90a Mon Sep 17 00:00:00 2001
From: Steven Price <steven.price@....com>
Date: Thu, 8 Nov 2018 13:43:56 +0000
Subject: [PATCH kvmtool] ARM PV time support

Signed-off-by: Steven Price <steven.price@....com>
---
 Makefile                 |  2 +-
 arm/kvm-cpu.c            |  4 ++++
 arm/pvtime.c             | 47 ++++++++++++++++++++++++++++++++++++++++
 include/kvm/arm-pvtime.h |  6 +++++
 4 files changed, 58 insertions(+), 1 deletion(-)
 create mode 100644 arm/pvtime.c
 create mode 100644 include/kvm/arm-pvtime.h

diff --git a/Makefile b/Makefile
index 3862112..a79956b 100644
--- a/Makefile
+++ b/Makefile
@@ -158,7 +158,7 @@ endif
 # ARM
 OBJS_ARM_COMMON		:= arm/fdt.o arm/gic.o arm/gicv2m.o arm/ioport.o \
 			   arm/kvm.o arm/kvm-cpu.o arm/pci.o arm/timer.o \
-			   arm/pmu.o
+			   arm/pmu.o arm/pvtime.o
 HDRS_ARM_COMMON		:= arm/include
 ifeq ($(ARCH), arm)
 	DEFINES		+= -DCONFIG_ARM
diff --git a/arm/kvm-cpu.c b/arm/kvm-cpu.c
index 7780251..c903b05 100644
--- a/arm/kvm-cpu.c
+++ b/arm/kvm-cpu.c
@@ -1,5 +1,6 @@
 #include "kvm/kvm.h"
 #include "kvm/kvm-cpu.h"
+#include "kvm/arm-pvtime.h"
 
 static int debug_fd;
 
@@ -122,6 +123,9 @@ struct kvm_cpu *kvm_cpu__arch_init(struct kvm *kvm, unsigned long cpu_id)
 	vcpu->cpu_compatible	= target->compatible;
 	vcpu->is_running	= true;
 
+	if (pvtime_vcpu_init(vcpu))
+		die("Unable to initialise pvtime");
+
 	return vcpu;
 }
 
diff --git a/arm/pvtime.c b/arm/pvtime.c
new file mode 100644
index 0000000..fc152d3
--- /dev/null
+++ b/arm/pvtime.c
@@ -0,0 +1,47 @@
+#include "kvm/kvm.h"
+#include "kvm/kvm-cpu.h"
+#include "kvm/arm-pvtime.h"
+
+#define PVTIME_BASE 0x10000000
+
+#define KVM_ARM_VCPU_PVTIME_CTRL	2
+#define   KVM_ARM_VCPU_PVTIME_IPA	0
+
+static int pvtime_init(struct kvm *kvm)
+{
+	char *mem;
+	int size = ALIGN(64 * kvm->cfg.nrcpus, PAGE_SIZE);
+
+	mem = mmap(NULL, size, PROT_RW, MAP_ANON_NORESERVE, -1, 0);
+	if (mem == MAP_FAILED)
+		return -ENOMEM;
+
+	if (kvm__register_dev_mem(kvm, PVTIME_BASE, size, mem))
+		return -EINVAL;
+
+	return 0;
+}
+
+base_init(pvtime_init);
+
+int pvtime_vcpu_init(struct kvm_cpu *vcpu)
+{
+	int err;
+	u64 st_paddr = PVTIME_BASE;
+
+	st_paddr += vcpu->cpu_id * 64;
+
+	struct kvm_device_attr st_base = {
+		.group = KVM_ARM_VCPU_PVTIME_CTRL,
+		.attr = KVM_ARM_VCPU_PVTIME_IPA,
+		.addr = (u64)&st_paddr
+	};
+
+	err = ioctl(vcpu->vcpu_fd, KVM_SET_DEVICE_ATTR, &st_base);
+	if (err) {
+		perror("ioctl st_base failed");
+		return err;
+	}
+
+	return 0;
+}
diff --git a/include/kvm/arm-pvtime.h b/include/kvm/arm-pvtime.h
new file mode 100644
index 0000000..f5db286
--- /dev/null
+++ b/include/kvm/arm-pvtime.h
@@ -0,0 +1,6 @@
+#ifndef ARM_PVTIME_H
+#define ARM_PVTIME_H
+
+int pvtime_vcpu_init(struct kvm_cpu *vcpu);
+
+#endif
-- 
2.20.1