From: Steven Price <steven.price@arm.com>
To: Andrew Jones <drjones@redhat.com>
Cc: "Marc Zyngier" <maz@kernel.org>, "Will Deacon" <will@kernel.org>,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu,
"Catalin Marinas" <catalin.marinas@arm.com>,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Russell King" <linux@armlinux.org.uk>,
"James Morse" <james.morse@arm.com>,
"Julien Thierry" <julien.thierry.kdev@gmail.com>,
"Suzuki K Pouloze" <suzuki.poulose@arm.com>,
"Mark Rutland" <mark.rutland@arm.com>,
kvm@vger.kernel.org, linux-doc@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4 10/10] arm64: Retrieve stolen time as paravirtualized guest
Date: Wed, 4 Sep 2019 17:01:11 +0100 [thread overview]
Message-ID: <329fa72e-5c92-602e-a010-2083366221d1@arm.com> (raw)
In-Reply-To: <20190903084703.hwpelmr7fikb32nj@kamzik.brq.redhat.com>
On 03/09/2019 09:47, Andrew Jones wrote:
> On Fri, Aug 30, 2019 at 09:42:55AM +0100, Steven Price wrote:
>> Enable paravirtualization features when running under a hypervisor
>> supporting the PV_TIME_ST hypercall.
>>
>> For each (v)CPU, we ask the hypervisor for the location of a shared
>> page which the hypervisor will use to report stolen time to us. We set
>> pv_time_ops to the stolen time function which simply reads the stolen
>> value from the shared page for a VCPU. We guarantee single-copy
>> atomicity using READ_ONCE which means we can also read the stolen
>> time for another VCPU than the currently running one while it is
>> potentially being updated by the hypervisor.
>>
>> Signed-off-by: Steven Price <steven.price@arm.com>
>> ---
>> arch/arm64/include/asm/paravirt.h | 9 +-
>> arch/arm64/kernel/paravirt.c | 148 ++++++++++++++++++++++++++++++
>> arch/arm64/kernel/time.c | 3 +
>> include/linux/cpuhotplug.h | 1 +
>> 4 files changed, 160 insertions(+), 1 deletion(-)
>>
>> diff --git a/arch/arm64/include/asm/paravirt.h b/arch/arm64/include/asm/paravirt.h
>> index 799d9dd6f7cc..125c26c42902 100644
>> --- a/arch/arm64/include/asm/paravirt.h
>> +++ b/arch/arm64/include/asm/paravirt.h
>> @@ -21,6 +21,13 @@ static inline u64 paravirt_steal_clock(int cpu)
>> {
>> return pv_ops.time.steal_clock(cpu);
>> }
>> -#endif
>> +
>> +int __init kvm_guest_init(void);
>> +
>> +#else
>> +
>> +#define kvm_guest_init()
>> +
>> +#endif // CONFIG_PARAVIRT
>>
>> #endif
>> diff --git a/arch/arm64/kernel/paravirt.c b/arch/arm64/kernel/paravirt.c
>> index 4cfed91fe256..5bf3be7ccf7e 100644
>> --- a/arch/arm64/kernel/paravirt.c
>> +++ b/arch/arm64/kernel/paravirt.c
>> @@ -6,13 +6,161 @@
>> * Author: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
>> */
>>
>> +#define pr_fmt(fmt) "kvmarm-pv: " fmt
>> +
>> +#include <linux/arm-smccc.h>
>> +#include <linux/cpuhotplug.h>
>> #include <linux/export.h>
>> +#include <linux/io.h>
>> #include <linux/jump_label.h>
>> +#include <linux/printk.h>
>> +#include <linux/psci.h>
>> +#include <linux/reboot.h>
>> +#include <linux/slab.h>
>> #include <linux/types.h>
>> +
>> #include <asm/paravirt.h>
>> +#include <asm/pvclock-abi.h>
>> +#include <asm/smp_plat.h>
>>
>> struct static_key paravirt_steal_enabled;
>> struct static_key paravirt_steal_rq_enabled;
>>
>> struct paravirt_patch_template pv_ops;
>> EXPORT_SYMBOL_GPL(pv_ops);
>> +
>> +struct kvmarm_stolen_time_region {
>> + struct pvclock_vcpu_stolen_time *kaddr;
>> +};
>> +
>> +static DEFINE_PER_CPU(struct kvmarm_stolen_time_region, stolen_time_region);
>> +
>> +static bool steal_acc = true;
>> +static int __init parse_no_stealacc(char *arg)
>> +{
>> + steal_acc = false;
>> + return 0;
>> +}
>> +
>> +early_param("no-steal-acc", parse_no_stealacc);
>
> Need to also add an 'ARM64' to the
> Documentation/admin-guide/kernel-parameters.txt entry for this.
Good point, thanks for the pointer.
Steve
next prev parent reply other threads:[~2019-09-04 16:09 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-30 8:42 [PATCH v4 00/10] arm64: Stolen time support Steven Price
2019-08-30 8:42 ` [PATCH v4 01/10] KVM: arm64: Document PV-time interface Steven Price
2019-08-30 14:47 ` Andrew Jones
2019-08-30 15:25 ` Steven Price
2019-09-02 12:52 ` Andrew Jones
2019-09-04 13:55 ` Steven Price
2019-09-04 14:22 ` Andrew Jones
2019-09-04 15:07 ` Steven Price
2019-08-30 8:42 ` [PATCH v4 02/10] KVM: arm/arm64: Factor out hypercall handling from PSCI code Steven Price
2019-09-02 7:06 ` kbuild test robot
2019-09-04 15:05 ` Steven Price
2019-09-02 13:07 ` kbuild test robot
2019-08-30 8:42 ` [PATCH v4 03/10] KVM: arm64: Implement PV_FEATURES call Steven Price
2019-08-30 8:42 ` [PATCH v4 04/10] KVM: Implement kvm_put_guest() Steven Price
2019-08-30 8:42 ` [PATCH v4 05/10] KVM: arm64: Support stolen time reporting via shared structure Steven Price
2019-08-30 9:42 ` Christoffer Dall
2019-08-30 9:52 ` Steven Price
2019-09-03 9:14 ` Zenghui Yu
2019-09-04 15:53 ` Steven Price
2019-08-30 8:42 ` [PATCH v4 06/10] KVM: Allow kvm_device_ops to be const Steven Price
2019-08-30 8:42 ` [PATCH v4 07/10] KVM: arm64: Provide VCPU attributes for stolen time Steven Price
2019-08-30 10:02 ` Marc Zyngier
2019-08-30 15:04 ` Steven Price
2019-08-30 8:42 ` [PATCH v4 08/10] arm/arm64: Provide a wrapper for SMCCC 1.1 calls Steven Price
2019-08-30 8:42 ` [PATCH v4 09/10] arm/arm64: Make use of the SMCCC 1.1 wrapper Steven Price
2019-08-30 8:42 ` [PATCH v4 10/10] arm64: Retrieve stolen time as paravirtualized guest Steven Price
2019-09-03 8:47 ` Andrew Jones
2019-09-04 16:01 ` Steven Price [this message]
2019-09-03 8:03 ` [PATCH v4 00/10] arm64: Stolen time support Andrew Jones
2019-09-03 8:49 ` Andrew Jones
2019-09-04 16:02 ` Steven Price
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