From:   isaku.yamahata@intel.com
To:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     isaku.yamahata@intel.com, isaku.yamahata@gmail.com,
        Paolo Bonzini <pbonzini@redhat.com>, erdemaktas@google.com,
        Sean Christopherson <seanjc@google.com>,
        Sagi Shahar <sagis@google.com>,
        David Matlack <dmatlack@google.com>,
        Kai Huang <kai.huang@intel.com>,
        Zhi Wang <zhi.wang.linux@gmail.com>
Subject: [PATCH v12 099/106] KVM: TDX: Add methods to ignore accesses to TSC
Date:   Mon, 27 Feb 2023 00:23:38 -0800
Message-Id: <9b5301bd28a90eece54d301ccb41bbbc39bda024.1677484918.git.isaku.yamahata@intel.com>
In-Reply-To: <cover.1677484918.git.isaku.yamahata@intel.com>
References: <cover.1677484918.git.isaku.yamahata@intel.com>
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From: Isaku Yamahata <isaku.yamahata@intel.com>

TDX protects TDX guest TSC state from VMM.  Implement access methods to
ignore guest TSC.

Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
 arch/x86/kvm/vmx/main.c | 44 +++++++++++++++++++++++++++++++++++++----
 1 file changed, 40 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index ed9c5f9f3413..340e76e1b59e 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -806,6 +806,42 @@ static u8 vt_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
 	return __vmx_get_mt_mask(vcpu, gfn, is_mmio, true);
 }
 
+static u64 vt_get_l2_tsc_offset(struct kvm_vcpu *vcpu)
+{
+	/* TDX doesn't support L2 guest at the moment. */
+	if (KVM_BUG_ON(is_td_vcpu(vcpu), vcpu->kvm))
+		return 0;
+
+	return vmx_get_l2_tsc_offset(vcpu);
+}
+
+static u64 vt_get_l2_tsc_multiplier(struct kvm_vcpu *vcpu)
+{
+	/* TDX doesn't support L2 guest at the moment. */
+	if (KVM_BUG_ON(is_td_vcpu(vcpu), vcpu->kvm))
+		return 0;
+
+	return vmx_get_l2_tsc_multiplier(vcpu);
+}
+
+static void vt_write_tsc_offset(struct kvm_vcpu *vcpu, u64 offset)
+{
+	/* In TDX, tsc offset can't be changed. */
+	if (is_td_vcpu(vcpu))
+		return;
+
+	vmx_write_tsc_offset(vcpu, offset);
+}
+
+static void vt_write_tsc_multiplier(struct kvm_vcpu *vcpu, u64 multiplier)
+{
+	/* In TDX, tsc multiplier can't be changed. */
+	if (is_td_vcpu(vcpu))
+		return;
+
+	vmx_write_tsc_multiplier(vcpu, multiplier);
+}
+
 static void vt_update_cpu_dirty_logging(struct kvm_vcpu *vcpu)
 {
 	if (KVM_BUG_ON(is_td_vcpu(vcpu), vcpu->kvm))
@@ -964,10 +1000,10 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
 
 	.has_wbinvd_exit = cpu_has_vmx_wbinvd_exit,
 
-	.get_l2_tsc_offset = vmx_get_l2_tsc_offset,
-	.get_l2_tsc_multiplier = vmx_get_l2_tsc_multiplier,
-	.write_tsc_offset = vmx_write_tsc_offset,
-	.write_tsc_multiplier = vmx_write_tsc_multiplier,
+	.get_l2_tsc_offset = vt_get_l2_tsc_offset,
+	.get_l2_tsc_multiplier = vt_get_l2_tsc_multiplier,
+	.write_tsc_offset = vt_write_tsc_offset,
+	.write_tsc_multiplier = vt_write_tsc_multiplier,
 
 	.load_mmu_pgd = vt_load_mmu_pgd,
 
-- 
2.25.1