linux-kernel - [PATCH 8/9] KVM: x86: Kill off __ex() and __kvm_handle_fault_on

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Message-Id: <20201231002702.2223707-9-seanjc@google.com>
Date:   Wed, 30 Dec 2020 16:27:01 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        "H. Peter Anvin" <hpa@...or.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        "David P . Reed" <dpreed@...pplum.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Uros Bizjak <ubizjak@...il.com>
Subject: [PATCH 8/9] KVM: x86: Kill off __ex() and __kvm_handle_fault_on_reboot()

Remove the __kvm_handle_fault_on_reboot() and __ex() macros now that all
VMX and SVM instructions use asm goto to handle the fault (or in the
case of VMREAD, completely custom logic).  Drop kvm_spurious_fault()'s
asmlinkage annotation as __kvm_handle_fault_on_reboot() was the only
flow that invoked it from assembly code.

Cc: Uros Bizjak <ubizjak@...il.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/include/asm/kvm_host.h | 25 +------------------------
 arch/x86/kvm/svm/sev.c          |  2 --
 arch/x86/kvm/svm/svm.c          |  2 --
 arch/x86/kvm/vmx/vmx_ops.h      |  2 --
 arch/x86/kvm/x86.c              |  9 ++++++++-
 5 files changed, 9 insertions(+), 31 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 3ab7b46087b7..51ba20ffaedb 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1634,30 +1634,7 @@ enum {
 #define kvm_arch_vcpu_memslots_id(vcpu) ((vcpu)->arch.hflags & HF_SMM_MASK ? 1 : 0)
 #define kvm_memslots_for_spte_role(kvm, role) __kvm_memslots(kvm, (role).smm)
 
-asmlinkage void kvm_spurious_fault(void);
-
-/*
- * Hardware virtualization extension instructions may fault if a
- * reboot turns off virtualization while processes are running.
- * Usually after catching the fault we just panic; during reboot
- * instead the instruction is ignored.
- */
-#define __kvm_handle_fault_on_reboot(insn)				\
-	"666: \n\t"							\
-	insn "\n\t"							\
-	"jmp	668f \n\t"						\
-	"667: \n\t"							\
-	"1: \n\t"							\
-	".pushsection .discard.instr_begin \n\t"			\
-	".long 1b - . \n\t"						\
-	".popsection \n\t"						\
-	"call	kvm_spurious_fault \n\t"				\
-	"1: \n\t"							\
-	".pushsection .discard.instr_end \n\t"				\
-	".long 1b - . \n\t"						\
-	".popsection \n\t"						\
-	"668: \n\t"							\
-	_ASM_EXTABLE(666b, 667b)
+void kvm_spurious_fault(void);
 
 #define KVM_ARCH_WANT_MMU_NOTIFIER
 int kvm_unmap_hva_range(struct kvm *kvm, unsigned long start, unsigned long end,
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 4511d7ccdb19..e7080e5056a4 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -26,8 +26,6 @@
 #include "cpuid.h"
 #include "trace.h"
 
-#define __ex(x) __kvm_handle_fault_on_reboot(x)
-
 static u8 sev_enc_bit;
 static int sev_flush_asids(void);
 static DECLARE_RWSEM(sev_deactivate_lock);
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 4308ab5ca27e..e4907e490c24 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -43,8 +43,6 @@
 #include "svm.h"
 #include "svm_ops.h"
 
-#define __ex(x) __kvm_handle_fault_on_reboot(x)
-
 MODULE_AUTHOR("Qumranet");
 MODULE_LICENSE("GPL");
 
diff --git a/arch/x86/kvm/vmx/vmx_ops.h b/arch/x86/kvm/vmx/vmx_ops.h
index 692b0c31c9c8..7b6fbe103c61 100644
--- a/arch/x86/kvm/vmx/vmx_ops.h
+++ b/arch/x86/kvm/vmx/vmx_ops.h
@@ -10,8 +10,6 @@
 #include "evmcs.h"
 #include "vmcs.h"
 
-#define __ex(x) __kvm_handle_fault_on_reboot(x)
-
 asmlinkage void vmread_error(unsigned long field, bool fault);
 __attribute__((regparm(0))) void vmread_error_trampoline(unsigned long field,
 							 bool fault);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 3f7c1fc7a3ce..836912b42030 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -412,7 +412,14 @@ int kvm_set_apic_base(struct kvm_vcpu *vcpu, struct msr_data *msr_info)
 }
 EXPORT_SYMBOL_GPL(kvm_set_apic_base);
 
-asmlinkage __visible noinstr void kvm_spurious_fault(void)
+/*
+ * Handle a fault on a hardware virtualization (VMX or SVM) instruction.
+ *
+ * Hardware virtualization extension instructions may fault if a reboot turns
+ * off virtualization while processes are running.  Usually after catching the
+ * fault we just panic; during reboot instead the instruction is ignored.
+ */
+noinstr void kvm_spurious_fault(void)
 {
 	/* Fault while not rebooting.  We want the trace. */
 	BUG_ON(!kvm_rebooting);
-- 
2.29.2.729.g45daf8777d-goog