linux-kernel - [RFC 15/19] KVM: x86/MMU: Refactor vmx_get_mt

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Message-Id: <20211110223010.1392399-16-bgardon@google.com>
Date:   Wed, 10 Nov 2021 14:30:06 -0800
From:   Ben Gardon <bgardon@...gle.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>, Peter Xu <peterx@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>,
        Peter Shier <pshier@...gle.com>,
        David Matlack <dmatlack@...gle.com>,
        Mingwei Zhang <mizhang@...gle.com>,
        Yulei Zhang <yulei.kernel@...il.com>,
        Wanpeng Li <kernellwp@...il.com>,
        Xiao Guangrong <xiaoguangrong.eric@...il.com>,
        Kai Huang <kai.huang@...el.com>,
        Keqian Zhu <zhukeqian1@...wei.com>,
        David Hildenbrand <david@...hat.com>,
        Ben Gardon <bgardon@...gle.com>
Subject: [RFC 15/19] KVM: x86/MMU: Refactor vmx_get_mt_mask

Remove the gotos from vmx_get_mt_mask to make it easier to separate out
the parts which do not depend on vcpu state.

No functional change intended.


Signed-off-by: Ben Gardon <bgardon@...gle.com>
---
 arch/x86/kvm/vmx/vmx.c | 23 +++++++----------------
 1 file changed, 7 insertions(+), 16 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 71f54d85f104..77f45c005f28 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6987,7 +6987,6 @@ static int __init vmx_check_processor_compat(void)
 static u64 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
 {
 	u8 cache;
-	u64 ipat = 0;
 
 	/* We wanted to honor guest CD/MTRR/PAT, but doing so could result in
 	 * memory aliases with conflicting memory types and sometimes MCEs.
@@ -7007,30 +7006,22 @@ static u64 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
 	 * EPT memory type is used to emulate guest CD/MTRR.
 	 */
 
-	if (is_mmio) {
-		cache = MTRR_TYPE_UNCACHABLE;
-		goto exit;
-	}
+	if (is_mmio)
+		return MTRR_TYPE_UNCACHABLE << VMX_EPT_MT_EPTE_SHIFT;
 
-	if (!kvm_arch_has_noncoherent_dma(vcpu->kvm)) {
-		ipat = VMX_EPT_IPAT_BIT;
-		cache = MTRR_TYPE_WRBACK;
-		goto exit;
-	}
+	if (!kvm_arch_has_noncoherent_dma(vcpu->kvm))
+		return (MTRR_TYPE_WRBACK << VMX_EPT_MT_EPTE_SHIFT) | VMX_EPT_IPAT_BIT;
 
 	if (kvm_read_cr0(vcpu) & X86_CR0_CD) {
-		ipat = VMX_EPT_IPAT_BIT;
 		if (kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_CD_NW_CLEARED))
 			cache = MTRR_TYPE_WRBACK;
 		else
 			cache = MTRR_TYPE_UNCACHABLE;
-		goto exit;
-	}
 
-	cache = kvm_mtrr_get_guest_memory_type(vcpu, gfn);
+		return (cache << VMX_EPT_MT_EPTE_SHIFT) | VMX_EPT_IPAT_BIT;
+	}
 
-exit:
-	return (cache << VMX_EPT_MT_EPTE_SHIFT) | ipat;
+	return kvm_mtrr_get_guest_memory_type(vcpu, gfn) << VMX_EPT_MT_EPTE_SHIFT;
 }
 
 static void vmcs_set_secondary_exec_control(struct vcpu_vmx *vmx, u32 new_ctl)
-- 
2.34.0.rc0.344.g81b53c2807-goog