linux-kernel - [PATCH v4 08/12] KVM: x86: centralize code to get CD=1 memtype when guest MTRRs are honored

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Date:   Fri, 14 Jul 2023 14:53:56 +0800
From:   Yan Zhao <yan.y.zhao@...el.com>
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     pbonzini@...hat.com, seanjc@...gle.com, chao.gao@...el.com,
        kai.huang@...el.com, robert.hoo.linux@...il.com,
        yuan.yao@...ux.intel.com, Yan Zhao <yan.y.zhao@...el.com>
Subject: [PATCH v4 08/12] KVM: x86: centralize code to get CD=1 memtype when guest MTRRs are honored

Centralize the code to get cache disabled memtype when guest MTRRs are
honored. If a TDP honors guest MTRRs, it is required to call the provided
API to get the memtype for CR0.CD=1.

This is the preparation patch for later implementation of fine-grained gfn
zap for CR0.CD toggles when guest MTRRs are honored.

No functional change intended.

Signed-off-by: Yan Zhao <yan.y.zhao@...el.com>
---
 arch/x86/kvm/mtrr.c    | 16 ++++++++++++++++
 arch/x86/kvm/vmx/vmx.c | 10 +++++-----
 arch/x86/kvm/x86.h     |  2 ++
 3 files changed, 23 insertions(+), 5 deletions(-)

diff --git a/arch/x86/kvm/mtrr.c b/arch/x86/kvm/mtrr.c
index 3ce58734ad22..64c6daa659c8 100644
--- a/arch/x86/kvm/mtrr.c
+++ b/arch/x86/kvm/mtrr.c
@@ -721,3 +721,19 @@ bool kvm_mtrr_check_gfn_range_consistency(struct kvm_vcpu *vcpu, gfn_t gfn,
 
 	return type == mtrr_default_type(mtrr_state);
 }
+
+/*
+ * this routine is supposed to be called when guest mtrrs are honored
+ */
+void kvm_honors_guest_mtrrs_get_cd_memtype(struct kvm_vcpu *vcpu,
+					   u8 *type, bool *ipat)
+{
+	if (kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_CD_NW_CLEARED)) {
+		*type = MTRR_TYPE_WRBACK;
+		*ipat = false;
+	} else {
+		*type = MTRR_TYPE_UNCACHABLE;
+		*ipat = true;
+	}
+}
+EXPORT_SYMBOL_GPL(kvm_honors_guest_mtrrs_get_cd_memtype);
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index c1e93678cea4..7fec1ee23b54 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -7573,11 +7573,11 @@ static u8 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
 		return (MTRR_TYPE_WRBACK << VMX_EPT_MT_EPTE_SHIFT) | VMX_EPT_IPAT_BIT;
 
 	if (kvm_read_cr0_bits(vcpu, X86_CR0_CD)) {
-		if (kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_CD_NW_CLEARED))
-			return MTRR_TYPE_WRBACK << VMX_EPT_MT_EPTE_SHIFT;
-		else
-			return (MTRR_TYPE_UNCACHABLE << VMX_EPT_MT_EPTE_SHIFT) |
-				VMX_EPT_IPAT_BIT;
+		bool ipat;
+		u8 cache;
+
+		kvm_honors_guest_mtrrs_get_cd_memtype(vcpu, &cache, &ipat);
+		return cache << VMX_EPT_MT_EPTE_SHIFT | (ipat ? VMX_EPT_IPAT_BIT : 0);
 	}
 
 	return kvm_mtrr_get_guest_memory_type(vcpu, gfn) << VMX_EPT_MT_EPTE_SHIFT;
diff --git a/arch/x86/kvm/x86.h b/arch/x86/kvm/x86.h
index 82e3dafc5453..e7733dc4dccc 100644
--- a/arch/x86/kvm/x86.h
+++ b/arch/x86/kvm/x86.h
@@ -313,6 +313,8 @@ int kvm_mtrr_set_msr(struct kvm_vcpu *vcpu, u32 msr, u64 data);
 int kvm_mtrr_get_msr(struct kvm_vcpu *vcpu, u32 msr, u64 *pdata);
 bool kvm_mtrr_check_gfn_range_consistency(struct kvm_vcpu *vcpu, gfn_t gfn,
 					  int page_num);
+void kvm_honors_guest_mtrrs_get_cd_memtype(struct kvm_vcpu *vcpu,
+					   u8 *type, bool *ipat);
 bool kvm_vector_hashing_enabled(void);
 void kvm_fixup_and_inject_pf_error(struct kvm_vcpu *vcpu, gva_t gva, u16 error_code);
 int x86_decode_emulated_instruction(struct kvm_vcpu *vcpu, int emulation_type,
-- 
2.17.1