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From:   Mathias Krause <minipli@grsecurity.net>
To:     kvm@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org,
        Sean Christopherson <seanjc@google.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Mathias Krause <minipli@grsecurity.net>
Subject: [PATCH v4 4/6] KVM: x86: Make use of kvm_read_cr*_bits() when testing bits
Date:   Wed, 22 Mar 2023 02:37:29 +0100
Message-Id: <20230322013731.102955-5-minipli@grsecurity.net>
In-Reply-To: <20230322013731.102955-1-minipli@grsecurity.net>
References: <20230322013731.102955-1-minipli@grsecurity.net>
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Make use of the kvm_read_cr{0,4}_bits() helper functions when we only
want to know the state of certain bits instead of the whole register.

This not only makes the intent cleaner, it also avoids a potential
VMREAD in case the tested bits aren't guest owned.

Signed-off-by: Mathias Krause <minipli@grsecurity.net>
---
 arch/x86/kvm/pmu.c     | 4 ++--
 arch/x86/kvm/vmx/vmx.c | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 612e6c70ce2e..f4aa170b5b97 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -540,9 +540,9 @@ int kvm_pmu_rdpmc(struct kvm_vcpu *vcpu, unsigned idx, u64 *data)
 	if (!pmc)
 		return 1;
 
-	if (!(kvm_read_cr4(vcpu) & X86_CR4_PCE) &&
+	if (!(kvm_read_cr4_bits(vcpu, X86_CR4_PCE)) &&
 	    (static_call(kvm_x86_get_cpl)(vcpu) != 0) &&
-	    (kvm_read_cr0(vcpu) & X86_CR0_PE))
+	    (kvm_read_cr0_bits(vcpu, X86_CR0_PE)))
 		return 1;
 
 	*data = pmc_read_counter(pmc) & mask;
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index d7bf14abdba1..8fc1a0c7856f 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -5517,7 +5517,7 @@ static int handle_cr(struct kvm_vcpu *vcpu)
 		break;
 	case 3: /* lmsw */
 		val = (exit_qualification >> LMSW_SOURCE_DATA_SHIFT) & 0x0f;
-		trace_kvm_cr_write(0, (kvm_read_cr0(vcpu) & ~0xful) | val);
+		trace_kvm_cr_write(0, (kvm_read_cr0_bits(vcpu, ~0xful) | val));
 		kvm_lmsw(vcpu, val);
 
 		return kvm_skip_emulated_instruction(vcpu);
@@ -7575,7 +7575,7 @@ static u8 vmx_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
 	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) {
+	if (kvm_read_cr0_bits(vcpu, X86_CR0_CD)) {
 		if (kvm_check_has_quirk(vcpu->kvm, KVM_X86_QUIRK_CD_NW_CLEARED))
 			cache = MTRR_TYPE_WRBACK;
 		else
-- 
2.39.2