linux-kernel - [PATCH v2 10/11] KVM: x86: SVM: use smram structs

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Date:   Tue, 21 Jun 2022 18:09:01 +0300
From:   Maxim Levitsky <mlevitsk@...hat.com>
To:     kvm@...r.kernel.org
Cc:     Sean Christopherson <seanjc@...gle.com>, x86@...nel.org,
        Kees Cook <keescook@...omium.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        linux-kernel@...r.kernel.org, "H. Peter Anvin" <hpa@...or.com>,
        Borislav Petkov <bp@...en8.de>, Joerg Roedel <joro@...tes.org>,
        Ingo Molnar <mingo@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Maxim Levitsky <mlevitsk@...hat.com>
Subject: [PATCH v2 10/11] KVM: x86: SVM: use smram structs

This removes the last user of put_smstate/GET_SMSTATE so
remove these functions as well.

Also add a sanity check that we don't attempt to enter the SMM
on non long mode capable guest CPU with a running nested guest.

Signed-off-by: Maxim Levitsky <mlevitsk@...hat.com>
---
 arch/x86/include/asm/kvm_host.h |  6 ------
 arch/x86/kvm/svm/svm.c          | 28 +++++++++++++++++-----------
 2 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 1038ccb7056a39..9e8467be96b4e6 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -2057,12 +2057,6 @@ static inline int kvm_cpu_get_apicid(int mps_cpu)
 #endif
 }
 
-#define put_smstate(type, buf, offset, val)                      \
-	*(type *)((buf) + (offset) - 0x7e00) = val
-
-#define GET_SMSTATE(type, buf, offset)		\
-	(*(type *)((buf) + (offset) - 0x7e00))
-
 int kvm_cpu_dirty_log_size(void);
 
 int memslot_rmap_alloc(struct kvm_memory_slot *slot, unsigned long npages);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 136298cfb3fb57..8dcbbe839bef36 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -4399,6 +4399,7 @@ static int svm_smi_allowed(struct kvm_vcpu *vcpu, bool for_injection)
 
 static int svm_enter_smm(struct kvm_vcpu *vcpu, char *smstate)
 {
+	struct kvm_smram_state_64 *smram = (struct kvm_smram_state_64 *)smstate;
 	struct vcpu_svm *svm = to_svm(vcpu);
 	struct kvm_host_map map_save;
 	int ret;
@@ -4406,10 +4407,17 @@ static int svm_enter_smm(struct kvm_vcpu *vcpu, char *smstate)
 	if (!is_guest_mode(vcpu))
 		return 0;
 
-	/* FED8h - SVM Guest */
-	put_smstate(u64, smstate, 0x7ed8, 1);
-	/* FEE0h - SVM Guest VMCB Physical Address */
-	put_smstate(u64, smstate, 0x7ee0, svm->nested.vmcb12_gpa);
+	/*
+	 * 32 bit SMRAM format doesn't preserve EFER and SVM state.
+	 * SVM should not be enabled by the userspace without marking
+	 * the CPU as at least long mode capable.
+	 */
+
+	if (!guest_cpuid_has(vcpu, X86_FEATURE_SVM))
+		return 1;
+
+	smram->svm_guest_flag = 1;
+	smram->svm_guest_vmcb_gpa = svm->nested.vmcb12_gpa;
 
 	svm->vmcb->save.rax = vcpu->arch.regs[VCPU_REGS_RAX];
 	svm->vmcb->save.rsp = vcpu->arch.regs[VCPU_REGS_RSP];
@@ -4446,9 +4454,9 @@ static int svm_enter_smm(struct kvm_vcpu *vcpu, char *smstate)
 
 static int svm_leave_smm(struct kvm_vcpu *vcpu, const char *smstate)
 {
+	struct kvm_smram_state_64 *smram = (struct kvm_smram_state_64 *)smstate;
 	struct vcpu_svm *svm = to_svm(vcpu);
 	struct kvm_host_map map, map_save;
-	u64 saved_efer, vmcb12_gpa;
 	struct vmcb *vmcb12;
 	int ret;
 
@@ -4456,18 +4464,16 @@ static int svm_leave_smm(struct kvm_vcpu *vcpu, const char *smstate)
 		return 0;
 
 	/* Non-zero if SMI arrived while vCPU was in guest mode. */
-	if (!GET_SMSTATE(u64, smstate, 0x7ed8))
+	if (!smram->svm_guest_flag)
 		return 0;
 
 	if (!guest_cpuid_has(vcpu, X86_FEATURE_SVM))
 		return 1;
 
-	saved_efer = GET_SMSTATE(u64, smstate, 0x7ed0);
-	if (!(saved_efer & EFER_SVME))
+	if (!(smram->efer & EFER_SVME))
 		return 1;
 
-	vmcb12_gpa = GET_SMSTATE(u64, smstate, 0x7ee0);
-	if (kvm_vcpu_map(vcpu, gpa_to_gfn(vmcb12_gpa), &map) == -EINVAL)
+	if (kvm_vcpu_map(vcpu, gpa_to_gfn(smram->svm_guest_vmcb_gpa), &map) == -EINVAL)
 		return 1;
 
 	ret = 1;
@@ -4493,7 +4499,7 @@ static int svm_leave_smm(struct kvm_vcpu *vcpu, const char *smstate)
 	vmcb12 = map.hva;
 	nested_copy_vmcb_control_to_cache(svm, &vmcb12->control);
 	nested_copy_vmcb_save_to_cache(svm, &vmcb12->save);
-	ret = enter_svm_guest_mode(vcpu, vmcb12_gpa, vmcb12, false);
+	ret = enter_svm_guest_mode(vcpu, smram->svm_guest_vmcb_gpa, vmcb12, false);
 
 	if (ret)
 		goto unmap_save;
-- 
2.26.3