[RFC PATCH v1 08/34] KVM: x86: add .set_ept_view()

["Adalbert Lazăr" <alazar@bitdefender.com>]

From: Marian Rotariu <marian.c.rotariu@gmail.com>

The introspection tool uses this function to check the hardware support
for EPT switching, which can be used either to singlestep vCPUs
on a unprotected EPT view.

Signed-off-by: Marian Rotariu <marian.c.rotariu@gmail.com>
Co-developed-by: Ștefan Șicleru <ssicleru@bitdefender.com>
Signed-off-by: Ștefan Șicleru <ssicleru@bitdefender.com>
Signed-off-by: Adalbert Lazăr <alazar@bitdefender.com>
---
 arch/x86/include/asm/kvm_host.h |  1 +
 arch/x86/kvm/vmx/vmx.c          | 35 ++++++++++++++++++++++++++++++++-
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 1035308940fe..300f7fc43987 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1309,6 +1309,7 @@ struct kvm_x86_ops {
 	bool (*get_vmfunc_status)(void);
 	bool (*get_eptp_switching_status)(void);
 	u16 (*get_ept_view)(struct kvm_vcpu *vcpu);
+	int (*set_ept_view)(struct kvm_vcpu *vcpu, u16 view);
 };
 
 struct kvm_x86_nested_ops {
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 2024ef4d9a74..0d39487ce5c6 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -4373,6 +4373,28 @@ static int vmx_alloc_eptp_list_page(struct vcpu_vmx *vmx)
 	return 0;
 }
 
+static int vmx_set_ept_view(struct kvm_vcpu *vcpu, u16 view)
+{
+	if (view >= KVM_MAX_EPT_VIEWS)
+		return -EINVAL;
+
+	if (to_vmx(vcpu)->eptp_list_pg) {
+		int r;
+
+		to_vmx(vcpu)->view = view;
+
+		/*
+		 * Reload mmu and make sure vmx_load_mmu_pgd() is called so that
+		 * VMCS::EPT_POINTER is updated accordingly
+		 */
+		kvm_mmu_unload(vcpu);
+		r = kvm_mmu_reload(vcpu);
+		WARN_ON_ONCE(r);
+	}
+
+	return 0;
+}
+
 #define VMX_XSS_EXIT_BITMAP 0
 
 /*
@@ -4463,9 +4485,15 @@ static void init_vmcs(struct vcpu_vmx *vmx)
 	if (cpu_has_vmx_encls_vmexit())
 		vmcs_write64(ENCLS_EXITING_BITMAP, -1ull);
 
-	if (vmx->eptp_list_pg)
+	if (vmx->eptp_list_pg) {
+		u64 vm_function_control;
+
 		vmcs_write64(EPTP_LIST_ADDRESS,
 				page_to_phys(vmx->eptp_list_pg));
+		vm_function_control = vmcs_read64(VM_FUNCTION_CONTROL);
+		vm_function_control |= VMX_VMFUNC_EPTP_SWITCHING;
+		vmcs_write64(VM_FUNCTION_CONTROL, vm_function_control);
+	}
 
 	if (vmx_pt_mode_is_host_guest()) {
 		memset(&vmx->pt_desc, 0, sizeof(vmx->pt_desc));
@@ -5965,6 +5993,10 @@ static void dump_eptp_list(void)
 
 	eptp_list = phys_to_virt(eptp_list_phys);
 
+	pr_err("VMFunctionControl=%08x VMFunctionControlHigh=%08x\n",
+	       vmcs_read32(VM_FUNCTION_CONTROL),
+	       vmcs_read32(VM_FUNCTION_CONTROL_HIGH));
+
 	pr_err("*** EPTP Switching ***\n");
 	pr_err("EPTP List Address: %p (phys %p)\n",
 		eptp_list, (void *)eptp_list_phys);
@@ -8251,6 +8283,7 @@ static struct kvm_x86_ops vmx_x86_ops __initdata = {
 	.get_vmfunc_status = vmx_get_vmfunc_status,
 	.get_eptp_switching_status = vmx_get_eptp_switching_status,
 	.get_ept_view = vmx_get_ept_view,
+	.set_ept_view = vmx_set_ept_view,
 };
 
 static __init int hardware_setup(void)
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