linux-kernel - [PATCH v2 2/3] KVM: VMX: Replace MSR_IA32_RTIT_OUTPUT_BASE

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Date:   Wed, 23 Sep 2020 09:36:28 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2 2/3] KVM: VMX: Replace MSR_IA32_RTIT_OUTPUT_BASE_MASK with helper function

Replace the subtly not-a-constant MSR_IA32_RTIT_OUTPUT_BASE_MASK with a
proper helper function to check whether or not the specified base is
valid.  Blindly referencing the local 'vcpu' is especially nasty.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/kvm/vmx/vmx.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index be82da055fc4..0d41faf63b57 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -146,9 +146,6 @@ module_param_named(preemption_timer, enable_preemption_timer, bool, S_IRUGO);
 	RTIT_STATUS_ERROR | RTIT_STATUS_STOPPED | \
 	RTIT_STATUS_BYTECNT))
 
-#define MSR_IA32_RTIT_OUTPUT_BASE_MASK \
-	(~((1UL << cpuid_maxphyaddr(vcpu)) - 1) | 0x7f)
-
 /*
  * These 2 parameters are used to config the controls for Pause-Loop Exiting:
  * ple_gap:    upper bound on the amount of time between two successive
@@ -1037,6 +1034,12 @@ static inline bool pt_can_write_msr(struct vcpu_vmx *vmx)
 	       !(vmx->pt_desc.guest.ctl & RTIT_CTL_TRACEEN);
 }
 
+static inline bool pt_output_base_valid(struct kvm_vcpu *vcpu, u64 base)
+{
+	/* The base must be 128-byte aligned and a legal physical address. */
+	return !(base & (~((1UL << cpuid_maxphyaddr(vcpu)) - 1) | 0x7f));
+}
+
 static inline void pt_load_msr(struct pt_ctx *ctx, u32 addr_range)
 {
 	u32 i;
@@ -2167,7 +2170,7 @@ static int vmx_set_msr(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 		    !intel_pt_validate_cap(vmx->pt_desc.caps,
 					   PT_CAP_single_range_output))
 			return 1;
-		if (data & MSR_IA32_RTIT_OUTPUT_BASE_MASK)
+		if (!pt_output_base_valid(vcpu, data))
 			return 1;
 		vmx->pt_desc.guest.output_base = data;
 		break;
-- 
2.28.0