linux-kernel - [PATCH 4.9 064/107] x86/KVM/VMX: Add find

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Message-Id: <20180814171524.876043377@linuxfoundation.org>
Date:   Tue, 14 Aug 2018 19:17:27 +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,
        Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        David Woodhouse <dwmw@...zon.co.uk>
Subject: [PATCH 4.9 064/107] x86/KVM/VMX: Add find_msr() helper function

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

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

From: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>

commit ca83b4a7f2d068da79a029d323024aa45decb250 upstream

.. to help find the MSR on either the guest or host MSR list.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
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 |   31 ++++++++++++++++++-------------
 1 file changed, 18 insertions(+), 13 deletions(-)

--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -1975,9 +1975,20 @@ static void clear_atomic_switch_msr_spec
 	vm_exit_controls_clearbit(vmx, exit);
 }
 
+static int find_msr(struct vmx_msrs *m, unsigned int msr)
+{
+	unsigned int i;
+
+	for (i = 0; i < m->nr; ++i) {
+		if (m->val[i].index == msr)
+			return i;
+	}
+	return -ENOENT;
+}
+
 static void clear_atomic_switch_msr(struct vcpu_vmx *vmx, unsigned msr)
 {
-	unsigned i;
+	int i;
 	struct msr_autoload *m = &vmx->msr_autoload;
 
 	switch (msr) {
@@ -1998,11 +2009,8 @@ static void clear_atomic_switch_msr(stru
 		}
 		break;
 	}
-	for (i = 0; i < m->guest.nr; ++i)
-		if (m->guest.val[i].index == msr)
-			break;
-
-	if (i == m->guest.nr)
+	i = find_msr(&m->guest, msr);
+	if (i < 0)
 		return;
 	--m->guest.nr;
 	--m->host.nr;
@@ -2026,7 +2034,7 @@ static void add_atomic_switch_msr_specia
 static void add_atomic_switch_msr(struct vcpu_vmx *vmx, unsigned msr,
 				  u64 guest_val, u64 host_val)
 {
-	unsigned i;
+	int i;
 	struct msr_autoload *m = &vmx->msr_autoload;
 
 	switch (msr) {
@@ -2061,16 +2069,13 @@ static void add_atomic_switch_msr(struct
 		wrmsrl(MSR_IA32_PEBS_ENABLE, 0);
 	}
 
-	for (i = 0; i < m->guest.nr; ++i)
-		if (m->guest.val[i].index == msr)
-			break;
-
+	i = find_msr(&m->guest, msr);
 	if (i == NR_AUTOLOAD_MSRS) {
 		printk_once(KERN_WARNING "Not enough msr switch entries. "
 				"Can't add msr %x\n", msr);
 		return;
-	} else if (i == m->guest.nr) {
-		++m->guest.nr;
+	} else if (i < 0) {
+		i = m->guest.nr++;
 		++m->host.nr;
 		vmcs_write32(VM_ENTRY_MSR_LOAD_COUNT, m->guest.nr);
 		vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, m->host.nr);