linux-kernel - [PATCH v2 1/2] KVM: x86: Kill off __ex() and __kvm_handle_fault_on

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Message-Id: <20210809173955.1710866-2-seanjc@google.com>
Date:   Mon,  9 Aug 2021 10:39:54 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
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>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Uros Bizjak <ubizjak@...il.com>,
        Like Xu <like.xu.linux@...il.com>
Subject: [PATCH v2 1/2] 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>
Cc: Like Xu <like.xu.linux@...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 4c567b05edad..56540b5befd0 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1798,30 +1798,7 @@ 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
 
diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 9f1585f40c85..19cdb73aa623 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -28,8 +28,6 @@
 #include "cpuid.h"
 #include "trace.h"
 
-#define __ex(x) __kvm_handle_fault_on_reboot(x)
-
 #ifndef CONFIG_KVM_AMD_SEV
 /*
  * When this config is not defined, SEV feature is not supported and APIs in
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index 9d72b1df426e..2b6632d4c76f 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -46,8 +46,6 @@
 #include "kvm_onhyperv.h"
 #include "svm_onhyperv.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 164b64f65a8f..c0d74b994b56 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 df71f5e3e23b..156564c34624 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -486,7 +486,14 @@ 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);
-- 
2.32.0.605.g8dce9f2422-goog