Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754909Ab3FATWa (ORCPT ); Sat, 1 Jun 2013 15:22:30 -0400 Received: from e23smtp03.au.ibm.com ([202.81.31.145]:32908 "EHLO e23smtp03.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755088Ab3FATWR (ORCPT ); Sat, 1 Jun 2013 15:22:17 -0400 From: Raghavendra K T To: , , , , , , Cc: linux-doc@vger.kernel.org, , Raghavendra K T , , , , , , , , , , , , , , , , , , , , Date: Sun, 02 Jun 2013 00:56:24 +0530 Message-Id: <20130601192624.5966.97025.sendpatchset@codeblue> In-Reply-To: <20130601192125.5966.35563.sendpatchset@codeblue> References: <20130601192125.5966.35563.sendpatchset@codeblue> Subject: [PATCH RFC V9 18/19] Documentation/kvm : Add documentation on Hypercalls and features used for PV spinlock X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13060119-6102-0000-0000-0000039EDC6A Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3102 Lines: 61 Documentation/kvm : Add documentation on Hypercalls and features used for PV spinlock From: Raghavendra K T KVM_HC_KICK_CPU hypercall added to wakeup halted vcpu in paravirtual spinlock enabled guest. KVM_FEATURE_PV_UNHALT enables guest to check whether pv spinlock can be enabled in guest. Thanks Vatsa for rewriting KVM_HC_KICK_CPU Signed-off-by: Srivatsa Vaddagiri Signed-off-by: Raghavendra K T --- Documentation/virtual/kvm/cpuid.txt | 4 ++++ Documentation/virtual/kvm/hypercalls.txt | 13 +++++++++++++ 2 files changed, 17 insertions(+) diff --git a/Documentation/virtual/kvm/cpuid.txt b/Documentation/virtual/kvm/cpuid.txt index 83afe65..654f43c 100644 --- a/Documentation/virtual/kvm/cpuid.txt +++ b/Documentation/virtual/kvm/cpuid.txt @@ -43,6 +43,10 @@ KVM_FEATURE_CLOCKSOURCE2 || 3 || kvmclock available at msrs KVM_FEATURE_ASYNC_PF || 4 || async pf can be enabled by || || writing to msr 0x4b564d02 ------------------------------------------------------------------------------ +KVM_FEATURE_PV_UNHALT || 6 || guest checks this feature bit + || || before enabling paravirtualized + || || spinlock support. +------------------------------------------------------------------------------ KVM_FEATURE_CLOCKSOURCE_STABLE_BIT || 24 || host will warn if no guest-side || || per-cpu warps are expected in || || kvmclock. diff --git a/Documentation/virtual/kvm/hypercalls.txt b/Documentation/virtual/kvm/hypercalls.txt index ea113b5..2a4da11 100644 --- a/Documentation/virtual/kvm/hypercalls.txt +++ b/Documentation/virtual/kvm/hypercalls.txt @@ -64,3 +64,16 @@ Purpose: To enable communication between the hypervisor and guest there is a shared page that contains parts of supervisor visible register state. The guest can map this shared page to access its supervisor register through memory using this hypercall. + +5. KVM_HC_KICK_CPU +------------------------ +Architecture: x86 +Status: active +Purpose: Hypercall used to wakeup a vcpu from HLT state +Usage example : A vcpu of a paravirtualized guest that is busywaiting in guest +kernel mode for an event to occur (ex: a spinlock to become available) can +execute HLT instruction once it has busy-waited for more than a threshold +time-interval. Execution of HLT instruction would cause the hypervisor to put +the vcpu to sleep until occurence of an appropriate event. Another vcpu of the +same guest can wakeup the sleeping vcpu by issuing KVM_HC_KICK_CPU hypercall, +specifying APIC ID of the vcpu to be wokenup. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/