linux-kernel - [PATCH v2 1/8] KVM: x86: use a separate asm-offsets.c file

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Message-Id: <20221108151532.1377783-2-pbonzini@redhat.com>
Date:   Tue,  8 Nov 2022 10:15:25 -0500
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     nathan@...nel.org, thomas.lendacky@....com,
        andrew.cooper3@...rix.com, peterz@...radead.org,
        jmattson@...gle.com, seanjc@...gle.com
Subject: [PATCH v2 1/8] KVM: x86: use a separate asm-offsets.c file

This already removes the ugly #includes from asm-offsets.c, but especially
it avoids a future error when asm-offsets will try to include svm/svm.h.

This would not work for kernel/asm-offsets.c, because svm/svm.h
includes kvm_cache_regs.h which is not in the include path when
compiling asm-offsets.c.  The problem is not there if the .c file is
in arch/x86/kvm.

Tested with both in-tree and separate-objtree compilation.

Suggested-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kernel/asm-offsets.c  |  6 ------
 arch/x86/kvm/Makefile          |  9 +++++++++
 arch/x86/kvm/kvm-asm-offsets.c | 18 ++++++++++++++++++
 arch/x86/kvm/vmx/vmenter.S     |  2 +-
 4 files changed, 28 insertions(+), 7 deletions(-)
 create mode 100644 arch/x86/kvm/kvm-asm-offsets.c

diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c
index cb50589a7102..437308004ef2 100644
--- a/arch/x86/kernel/asm-offsets.c
+++ b/arch/x86/kernel/asm-offsets.c
@@ -19,7 +19,6 @@
 #include <asm/suspend.h>
 #include <asm/tlbflush.h>
 #include <asm/tdx.h>
-#include "../kvm/vmx/vmx.h"
 
 #ifdef CONFIG_XEN
 #include <xen/interface/xen.h>
@@ -108,9 +107,4 @@ static void __used common(void)
 	OFFSET(TSS_sp0, tss_struct, x86_tss.sp0);
 	OFFSET(TSS_sp1, tss_struct, x86_tss.sp1);
 	OFFSET(TSS_sp2, tss_struct, x86_tss.sp2);
-
-	if (IS_ENABLED(CONFIG_KVM_INTEL)) {
-		BLANK();
-		OFFSET(VMX_spec_ctrl, vcpu_vmx, spec_ctrl);
-	}
 }
diff --git a/arch/x86/kvm/Makefile b/arch/x86/kvm/Makefile
index 30f244b64523..a02cf9baacc8 100644
--- a/arch/x86/kvm/Makefile
+++ b/arch/x86/kvm/Makefile
@@ -34,3 +34,12 @@ endif
 obj-$(CONFIG_KVM)	+= kvm.o
 obj-$(CONFIG_KVM_INTEL)	+= kvm-intel.o
 obj-$(CONFIG_KVM_AMD)	+= kvm-amd.o
+
+AFLAGS_vmx/vmenter.o    := -iquote $(obj)
+$(obj)/vmx/vmenter.o: $(obj)/kvm-asm-offsets.h
+
+$(obj)/kvm-asm-offsets.h: $(obj)/kvm-asm-offsets.s FORCE
+	$(call filechk,offsets,__KVM_ASM_OFFSETS_H__)
+
+targets += kvm-asm-offsets.s
+clean-files += kvm-asm-offsets.h
diff --git a/arch/x86/kvm/kvm-asm-offsets.c b/arch/x86/kvm/kvm-asm-offsets.c
new file mode 100644
index 000000000000..9d84f2b32d7f
--- /dev/null
+++ b/arch/x86/kvm/kvm-asm-offsets.c
@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Generate definitions needed by assembly language modules.
+ * This code generates raw asm output which is post-processed to extract
+ * and format the required data.
+ */
+#define COMPILE_OFFSETS
+
+#include <linux/kbuild.h>
+#include "vmx/vmx.h"
+
+static void __used common(void)
+{
+	if (IS_ENABLED(CONFIG_KVM_INTEL)) {
+		BLANK();
+		OFFSET(VMX_spec_ctrl, vcpu_vmx, spec_ctrl);
+	}
+}
diff --git a/arch/x86/kvm/vmx/vmenter.S b/arch/x86/kvm/vmx/vmenter.S
index 8477d8bdd69c..0b5db4de4d09 100644
--- a/arch/x86/kvm/vmx/vmenter.S
+++ b/arch/x86/kvm/vmx/vmenter.S
@@ -1,12 +1,12 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #include <linux/linkage.h>
 #include <asm/asm.h>
-#include <asm/asm-offsets.h>
 #include <asm/bitsperlong.h>
 #include <asm/kvm_vcpu_regs.h>
 #include <asm/nospec-branch.h>
 #include <asm/percpu.h>
 #include <asm/segment.h>
+#include "kvm-asm-offsets.h"
 #include "run_flags.h"
 
 #define WORD_SIZE (BITS_PER_LONG / 8)
-- 
2.31.1