linux-kernel - [PATCH] KVM: x86: small optimization for is_mtrr

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Message-ID: <1583376535-27255-1-git-send-email-linmiaohe@huawei.com>
Date:   Thu, 5 Mar 2020 10:48:55 +0800
From:   linmiaohe <linmiaohe@...wei.com>
To:     <pbonzini@...hat.com>, <rkrcmar@...hat.com>,
        <sean.j.christopherson@...el.com>, <vkuznets@...hat.com>,
        <jmattson@...gle.com>, <joro@...tes.org>, <tglx@...utronix.de>,
        <mingo@...hat.com>, <bp@...en8.de>, <hpa@...or.com>
CC:     <linmiaohe@...wei.com>, <kvm@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <x86@...nel.org>
Subject: [PATCH] KVM: x86: small optimization for is_mtrr_mask calculation

From: Miaohe Lin <linmiaohe@...wei.com>

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

Signed-off-by: Miaohe Lin <linmiaohe@...wei.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