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From: Vitaly Kuznetsov <vkuznets@redhat.com>
To: kvm@vger.kernel.org
Cc: "Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Roman Kagan" <rkagan@virtuozzo.com>,
	"K. Y. Srinivasan" <kys@microsoft.com>,
	"Haiyang Zhang" <haiyangz@microsoft.com>,
	"Stephen Hemminger" <sthemmin@microsoft.com>,
	"Michael Kelley (EOSG)" <Michael.H.Kelley@microsoft.com>,
	"Jim Mattson" <jmattson@google.com>,
	"Liran Alon" <liran.alon@oracle.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH v5 07/12] x86/kvm/hyperv: don't clear VP assist pages on init
Date: Thu, 13 Sep 2018 19:05:17 +0200	[thread overview]
Message-ID: <20180913170522.24876-8-vkuznets@redhat.com> (raw)
In-Reply-To: <20180913170522.24876-1-vkuznets@redhat.com>

VP assist pages may hold valuable data which needs to be preserved across
migration. Clean PV EOI portion of the data on init, the guest is
responsible for making sure there's no garbage in the rest.

This will be used for nVMX migration, eVMCS address needs to be preserved.

Signed-off-by: Vitaly Kuznetsov <vkuznets@redhat.com>
---
 arch/x86/kvm/hyperv.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c
index b1655d01c368..ae3e2e0de680 100644
--- a/arch/x86/kvm/hyperv.c
+++ b/arch/x86/kvm/hyperv.c
@@ -1080,7 +1080,13 @@ static int kvm_hv_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data, bool host)
 		addr = kvm_vcpu_gfn_to_hva(vcpu, gfn);
 		if (kvm_is_error_hva(addr))
 			return 1;
-		if (__clear_user((void __user *)addr, PAGE_SIZE))
+
+		/*
+		 * Clear apic_assist portion of f(struct hv_vp_assist_page
+		 * only, there can be valuable data in the rest which needs
+		 * to be preserved e.g. on migration.
+		 */
+		if (__clear_user((void __user *)addr, sizeof(u32)))
 			return 1;
 		hv->hv_vapic = data;
 		kvm_vcpu_mark_page_dirty(vcpu, gfn);
-- 
2.14.4


  parent reply	other threads:[~2018-09-13 17:35 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-13 17:05 [PATCH v5 00/12] KVM: nVMX: Enlightened VMCS for Hyper-V on KVM Vitaly Kuznetsov
2018-09-13 17:05 ` [PATCH v5 01/12] KVM: hyperv: define VP assist page helpers Vitaly Kuznetsov
2018-09-13 17:05 ` [PATCH v5 02/12] KVM: VMX: refactor evmcs_sanitize_exec_ctrls() Vitaly Kuznetsov
2018-09-13 17:05 ` [PATCH v5 03/12] KVM: nVMX: add KVM_CAP_HYPERV_ENLIGHTENED_VMCS capability Vitaly Kuznetsov
2018-09-13 17:05 ` [PATCH v5 04/12] KVM: nVMX: add enlightened VMCS state Vitaly Kuznetsov
2018-09-13 17:05 ` [PATCH v5 05/12] KVM: nVMX: implement enlightened VMPTRLD and VMCLEAR Vitaly Kuznetsov
2018-09-13 17:05 ` [PATCH v5 06/12] KVM: nVMX: optimize prepare_vmcs02{,_full} for Enlightened VMCS case Vitaly Kuznetsov
2018-09-13 17:05 ` Vitaly Kuznetsov [this message]
2018-09-13 17:05 ` [PATCH v5 08/12] x86/kvm/lapic: preserve gfn_to_hva_cache len on cache reinit Vitaly Kuznetsov
2018-09-13 17:05 ` [PATCH v5 09/12] x86/kvm/nVMX: allow bare VMXON state migration Vitaly Kuznetsov
2018-09-13 19:21   ` Jim Mattson
2018-09-14  7:49     ` Vitaly Kuznetsov
2018-09-14 16:51       ` Jim Mattson
2018-10-15 17:09   ` Paolo Bonzini
2018-10-16 13:59     ` Vitaly Kuznetsov
2018-09-13 17:05 ` [PATCH v5 10/12] x86/kvm/nVMX: nested state migration for Enlightened VMCS Vitaly Kuznetsov
2018-09-13 17:05 ` [PATCH v5 11/12] tools/headers: update kvm.h Vitaly Kuznetsov
2018-09-13 17:05 ` [PATCH v5 12/12] KVM: selftests: add Enlightened VMCS test Vitaly Kuznetsov

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