Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   linmiaohe <linmiaohe@huawei.com>
To:     <pbonzini@redhat.com>, <rkrcmar@redhat.com>,
        <sean.j.christopherson@intel.com>, <vkuznets@redhat.com>,
        <jmattson@google.com>, <joro@8bytes.org>, <tglx@linutronix.de>,
        <mingo@redhat.com>, <bp@alien8.de>, <hpa@zytor.com>
CC:     <linmiaohe@huawei.com>, <kvm@vger.kernel.org>,
        <linux-kernel@vger.kernel.org>, <x86@kernel.org>
Subject: [PATCH] KVM: x86: small optimization for is_mtrr_mask calculation
Date:   Thu, 5 Mar 2020 10:48:55 +0800
Message-ID: <1583376535-27255-1-git-send-email-linmiaohe@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Miaohe Lin <linmiaohe@huawei.com>

We can get is_mtrr_mask by calculating (msr - 0x200) % 2 directly.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
 arch/x86/kvm/mtrr.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/mtrr.c b/arch/x86/kvm/mtrr.c
index 7f0059aa30e1..a98701d9f2bf 100644
--- a/arch/x86/kvm/mtrr.c
+++ b/arch/x86/kvm/mtrr.c
@@ -348,7 +348,7 @@ static void set_var_mtrr_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data)
 	int index, is_mtrr_mask;
 
 	index = (msr - 0x200) / 2;
-	is_mtrr_mask = msr - 0x200 - 2 * index;
+	is_mtrr_mask = (msr - 0x200) % 2;
 	cur = &mtrr_state->var_ranges[index];
 
 	/* remove the entry if it's in the list. */
@@ -424,7 +424,7 @@ int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata)
 		int is_mtrr_mask;
 
 		index = (msr - 0x200) / 2;
-		is_mtrr_mask = msr - 0x200 - 2 * index;
+		is_mtrr_mask = (msr - 0x200) % 2;
 		if (!is_mtrr_mask)
 			*pdata = vcpu->arch.mtrr_state.var_ranges[index].base;
 		else
-- 
2.19.1