linux-kernel - [PATCH 3/6] KVM: x86: Add dedicated emulator helper for grabbing CPUID.maxphyaddr

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Date:   Mon,  2 Mar 2020 11:57:33 -0800
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, Jan Kiszka <jan.kiszka@...mens.com>,
        Xiaoyao Li <xiaoyao.li@...el.com>
Subject: [PATCH 3/6] KVM: x86: Add dedicated emulator helper for grabbing CPUID.maxphyaddr

Add a helper to retrieve cpuid_maxphyaddr() instead of manually
calculating the value in the emulator via raw CPUID output.  In addition
to consolidating logic, this also paves the way toward simplifying
kvm_cpuid(), whose somewhat confusing return value exists purely to
support the emulator's maxphyaddr calculation.

No functional change intended.

Signed-off-by: Sean Christopherson <sean.j.christopherson@...el.com>
---
 arch/x86/include/asm/kvm_emulate.h |  1 +
 arch/x86/kvm/emulate.c             | 10 +---------
 arch/x86/kvm/x86.c                 |  6 ++++++
 3 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/arch/x86/include/asm/kvm_emulate.h b/arch/x86/include/asm/kvm_emulate.h
index bf5f5e476f65..ded06515d30f 100644
--- a/arch/x86/include/asm/kvm_emulate.h
+++ b/arch/x86/include/asm/kvm_emulate.h
@@ -222,6 +222,7 @@ struct x86_emulate_ops {
 
 	bool (*get_cpuid)(struct x86_emulate_ctxt *ctxt, u32 *eax, u32 *ebx,
 			  u32 *ecx, u32 *edx, bool check_limit);
+	int (*get_cpuid_maxphyaddr)(struct x86_emulate_ctxt *ctxt);
 	bool (*guest_has_long_mode)(struct x86_emulate_ctxt *ctxt);
 	bool (*guest_has_movbe)(struct x86_emulate_ctxt *ctxt);
 	bool (*guest_has_fxsr)(struct x86_emulate_ctxt *ctxt);
diff --git a/arch/x86/kvm/emulate.c b/arch/x86/kvm/emulate.c
index dd19fb3539e0..bf02ed51e90f 100644
--- a/arch/x86/kvm/emulate.c
+++ b/arch/x86/kvm/emulate.c
@@ -4244,16 +4244,8 @@ static int check_cr_write(struct x86_emulate_ctxt *ctxt)
 
 		ctxt->ops->get_msr(ctxt, MSR_EFER, &efer);
 		if (efer & EFER_LMA) {
-			u64 maxphyaddr;
-			u32 eax, ebx, ecx, edx;
+			int maxphyaddr = ctxt->ops->get_cpuid_maxphyaddr(ctxt);
 
-			eax = 0x80000008;
-			ecx = 0;
-			if (ctxt->ops->get_cpuid(ctxt, &eax, &ebx, &ecx,
-						 &edx, false))
-				maxphyaddr = eax & 0xff;
-			else
-				maxphyaddr = 36;
 			rsvd = rsvd_bits(maxphyaddr, 63);
 			if (ctxt->ops->get_cr(ctxt, 4) & X86_CR4_PCIDE)
 				rsvd &= ~X86_CR3_PCID_NOFLUSH;
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ddd1d296bd20..5467ee71c25b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -6209,6 +6209,11 @@ static bool emulator_get_cpuid(struct x86_emulate_ctxt *ctxt,
 	return kvm_cpuid(emul_to_vcpu(ctxt), eax, ebx, ecx, edx, check_limit);
 }
 
+static int emulator_get_cpuid_maxphyaddr(struct x86_emulate_ctxt *ctxt)
+{
+	return cpuid_maxphyaddr(emul_to_vcpu(ctxt));
+}
+
 static bool emulator_guest_has_long_mode(struct x86_emulate_ctxt *ctxt)
 {
 	return guest_cpuid_has(emul_to_vcpu(ctxt), X86_FEATURE_LM);
@@ -6301,6 +6306,7 @@ static const struct x86_emulate_ops emulate_ops = {
 	.fix_hypercall       = emulator_fix_hypercall,
 	.intercept           = emulator_intercept,
 	.get_cpuid           = emulator_get_cpuid,
+	.get_cpuid_maxphyaddr= emulator_get_cpuid_maxphyaddr,
 	.guest_has_long_mode = emulator_guest_has_long_mode,
 	.guest_has_movbe     = emulator_guest_has_movbe,
 	.guest_has_fxsr      = emulator_guest_has_fxsr,
-- 
2.24.1