linux-kernel - [RFC PATCH 44/73] KVM: x86/PVM: Implement TSC related callbacks

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Message-Id: <20240226143630.33643-45-jiangshanlai@gmail.com>
Date: Mon, 26 Feb 2024 22:36:01 +0800
From: Lai Jiangshan <jiangshanlai@...il.com>
To: linux-kernel@...r.kernel.org
Cc: Lai Jiangshan <jiangshan.ljs@...group.com>,
	Hou Wenlong <houwenlong.hwl@...group.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Sean Christopherson <seanjc@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Borislav Petkov <bp@...en8.de>,
	Ingo Molnar <mingo@...hat.com>,
	kvm@...r.kernel.org,
	Paolo Bonzini <pbonzini@...hat.com>,
	x86@...nel.org,
	Kees Cook <keescook@...omium.org>,
	Juergen Gross <jgross@...e.com>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	"H. Peter Anvin" <hpa@...or.com>
Subject: [RFC PATCH 44/73] KVM: x86/PVM: Implement TSC related callbacks

From: Lai Jiangshan <jiangshan.ljs@...group.com>

Without hardware assistance, TSC offset and TSC multiplier are not
supported in PVM. Therefore, the guest uses the host TSC directly, which
means the TSC offset is 0. Although it currently works correctly, a
proper ABI is needed to describe it.

Signed-off-by: Lai Jiangshan <jiangshan.ljs@...group.com>
Signed-off-by: Hou Wenlong <houwenlong.hwl@...group.com>
---
 arch/x86/kvm/pvm/pvm.c | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/arch/x86/kvm/pvm/pvm.c b/arch/x86/kvm/pvm/pvm.c
index 138d0c255cb8..f2cd1a1c199d 100644
--- a/arch/x86/kvm/pvm/pvm.c
+++ b/arch/x86/kvm/pvm/pvm.c
@@ -725,6 +725,28 @@ static int pvm_check_intercept(struct kvm_vcpu *vcpu,
 	return X86EMUL_CONTINUE;
 }
 
+static u64 pvm_get_l2_tsc_offset(struct kvm_vcpu *vcpu)
+{
+	return 0;
+}
+
+static u64 pvm_get_l2_tsc_multiplier(struct kvm_vcpu *vcpu)
+{
+	return 0;
+}
+
+static void pvm_write_tsc_offset(struct kvm_vcpu *vcpu)
+{
+	// TODO: add proper ABI and make guest use host TSC
+	vcpu->arch.tsc_offset = 0;
+	vcpu->arch.l1_tsc_offset = 0;
+}
+
+static void pvm_write_tsc_multiplier(struct kvm_vcpu *vcpu)
+{
+	// TODO: add proper ABI and make guest use host TSC
+}
+
 static void pvm_set_msr_linear_address_range(struct vcpu_pvm *pvm,
 					     u64 pml4_i_s, u64 pml4_i_e,
 					     u64 pml5_i_s, u64 pml5_i_e)
@@ -2776,6 +2798,10 @@ static struct kvm_x86_ops pvm_x86_ops __initdata = {
 	.complete_emulated_msr = kvm_complete_insn_gp,
 	.vcpu_deliver_sipi_vector = kvm_vcpu_deliver_sipi_vector,
 
+	.get_l2_tsc_offset = pvm_get_l2_tsc_offset,
+	.get_l2_tsc_multiplier = pvm_get_l2_tsc_multiplier,
+	.write_tsc_offset = pvm_write_tsc_offset,
+	.write_tsc_multiplier = pvm_write_tsc_multiplier,
 	.check_emulate_instruction = pvm_check_emulate_instruction,
 	.disallowed_va = pvm_disallowed_va,
 	.vcpu_gpc_refresh = pvm_vcpu_gpc_refresh,
-- 
2.19.1.6.gb485710b