From 93286261de1b46339aa27cd4c639b21778f6cade Mon Sep 17 00:00:00 2001 From: Vitaly Kuznetsov Date: Wed, 24 Jan 2018 14:23:33 +0100 Subject: x86/hyperv: Reenlightenment notifications support MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Hyper-V supports Live Migration notification. This is supposed to be used in conjunction with TSC emulation: when a VM is migrated to a host with different TSC frequency for some short period the host emulates the accesses to TSC and sends an interrupt to notify about the event. When the guest is done updating everything it can disable TSC emulation and everything will start working fast again. These notifications weren't required until now as Hyper-V guests are not supposed to use TSC as a clocksource: in Linux the TSC is even marked as unstable on boot. Guests normally use 'tsc page' clocksource and host updates its values on migrations automatically. Things change when with nested virtualization: even when the PV clocksources (kvm-clock or tsc page) are passed through to the nested guests the TSC frequency and frequency changes need to be know.. Hyper-V Top Level Functional Specification (as of v5.0b) wrongly specifies EAX:BIT(12) of CPUID:0x40000009 as the feature identification bit. The right one to check is EAX:BIT(13) of CPUID:0x40000003. I was assured that the fix in on the way. Signed-off-by: Vitaly Kuznetsov Signed-off-by: Thomas Gleixner Reviewed-by: Thomas Gleixner Cc: Stephen Hemminger Cc: kvm@vger.kernel.org Cc: Radim Krčmář Cc: Haiyang Zhang Cc: "Michael Kelley (EOSG)" Cc: Roman Kagan Cc: Andy Lutomirski Cc: devel@linuxdriverproject.org Cc: Paolo Bonzini Cc: "K. Y. Srinivasan" Cc: Cathy Avery Cc: Mohammed Gamal Link: https://lkml.kernel.org/r/20180124132337.30138-4-vkuznets@redhat.com --- arch/x86/entry/entry_32.S | 3 +++ 1 file changed, 3 insertions(+) (limited to 'arch/x86/entry/entry_32.S') diff --git a/arch/x86/entry/entry_32.S b/arch/x86/entry/entry_32.S index 2a35b1e0fb90..7a796eeddf99 100644 --- a/arch/x86/entry/entry_32.S +++ b/arch/x86/entry/entry_32.S @@ -895,6 +895,9 @@ BUILD_INTERRUPT3(xen_hvm_callback_vector, HYPERVISOR_CALLBACK_VECTOR, BUILD_INTERRUPT3(hyperv_callback_vector, HYPERVISOR_CALLBACK_VECTOR, hyperv_vector_handler) +BUILD_INTERRUPT3(hyperv_reenlightenment_vector, HYPERV_REENLIGHTENMENT_VECTOR, + hyperv_reenlightenment_intr) + #endif /* CONFIG_HYPERV */ ENTRY(page_fault) -- cgit v1.2.3