linux-kernel - [PATCH 4.9 090/107] x86/KVM/VMX: Dont set l1tf_flush_l1d from vmx_handle_external

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Message-Id: <20180814171526.383096851@linuxfoundation.org>
Date:   Tue, 14 Aug 2018 19:17:53 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Nicolai Stange <nstange@...e.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        David Woodhouse <dwmw@...zon.co.uk>
Subject: [PATCH 4.9 090/107] x86/KVM/VMX: Dont set l1tf_flush_l1d from vmx_handle_external_intr()

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Nicolai Stange <nstange@...e.de>

commit 18b57ce2eb8c8b9a24174a89250cf5f57c76ecdc upstream

For VMEXITs caused by external interrupts, vmx_handle_external_intr()
indirectly calls into the interrupt handlers through the host's IDT.

It follows that these interrupts get accounted for in the
kvm_cpu_l1tf_flush_l1d per-cpu flag.

The subsequently executed vmx_l1d_flush() will thus be aware that some
interrupts have happened and conduct a L1d flush anyway.

Setting l1tf_flush_l1d from vmx_handle_external_intr() isn't needed
anymore. Drop it.

Signed-off-by: Nicolai Stange <nstange@...e.de>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Signed-off-by: David Woodhouse <dwmw@...zon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 arch/x86/kvm/vmx.c |    1 -
 1 file changed, 1 deletion(-)

--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -8929,7 +8929,6 @@ static void vmx_handle_external_intr(str
 			[ss]"i"(__KERNEL_DS),
 			[cs]"i"(__KERNEL_CS)
 			);
-		vcpu->arch.l1tf_flush_l1d = true;
 	}
 }
 STACK_FRAME_NON_STANDARD(vmx_handle_external_intr);