KVM: MIPS: Hardcode callbacks to hardware virtualization extensions

Now that KVM no longer supports trap-and-emulate (see commit 45c7e8af4a5e
"MIPS: Remove KVM_TE support"), hardcode the MIPS callbacks to the
virtualization callbacks.

Harcoding the callbacks eliminates the technically-unnecessary check on
non-NULL kvm_mips_callbacks in kvm_arch_init().  MIPS has never supported
multiple in-tree modules, i.e. barring an out-of-tree module, where
copying and renaming kvm.ko counts as "out-of-tree", KVM could never
encounter a non-NULL set of callbacks during module init.

The callback check is also subtly broken, as it is not thread safe,
i.e. if there were multiple modules, loading both concurrently would
create a race between checking and setting kvm_mips_callbacks.

Given that out-of-tree shenanigans are not the kernel's responsibility,
hardcode the callbacks to simplify the code.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20221130230934.1014142-22-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/mips/include/asm/kvm_host.h b/arch/mips/include/asm/kvm_host.h
index 28f0ba97db71351201a555285a8af023cae6840f..2803c9c21ef9b6031734e118b6818c5765e07ecf 100644 (file)
--- a/arch/mips/include/asm/kvm_host.h
+++ b/arch/mips/include/asm/kvm_host.h
@@ -758,7 +758,7 @@ struct kvm_mips_callbacks {
        void (*vcpu_reenter)(struct kvm_vcpu *vcpu);
 };
 extern struct kvm_mips_callbacks *kvm_mips_callbacks;
-int kvm_mips_emulation_init(struct kvm_mips_callbacks **install_callbacks);
+int kvm_mips_emulation_init(void);
 
 /* Debug: dump vcpu state */
 int kvm_arch_vcpu_dump_regs(struct kvm_vcpu *vcpu);

diff --git a/arch/mips/kvm/Makefile b/arch/mips/kvm/Makefile
index 21ff75bcdbc44661be505bf0f41cdd63ea72e9fd..805aeea2166e59c793267d1def5c43070abd6187 100644 (file)
--- a/arch/mips/kvm/Makefile
+++ b/arch/mips/kvm/Makefile
@@ -17,4 +17,4 @@ kvm-$(CONFIG_CPU_LOONGSON64) += loongson_ipi.o
 
 kvm-y          += vz.o
 obj-$(CONFIG_KVM)      += kvm.o
-obj-y                  += callback.o tlb.o
+obj-y                  += tlb.o

diff --git a/arch/mips/kvm/callback.c b/arch/mips/kvm/callback.c
deleted file mode 100644 (file)
index d88aa21..0000000
--- a/arch/mips/kvm/callback.c
+++ /dev/null
@@ -1,14 +0,0 @@
-/*
- * This file is subject to the terms and conditions of the GNU General Public
- * License.  See the file "COPYING" in the main directory of this archive
- * for more details.
- *
- * Copyright (C) 2012  MIPS Technologies, Inc.  All rights reserved.
- * Authors: Yann Le Du <ledu@kymasys.com>
- */
-
-#include <linux/export.h>
-#include <linux/kvm_host.h>
-
-struct kvm_mips_callbacks *kvm_mips_callbacks;
-EXPORT_SYMBOL_GPL(kvm_mips_callbacks);

diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index af29490d9740c26828f9c7ebe8bbf469be942020..f0a6c245d1fffd51eded321d8ad05833c2f1086c 100644 (file)
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -1012,17 +1012,12 @@ long kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg)
 
 int kvm_arch_init(void *opaque)
 {
-       if (kvm_mips_callbacks) {
-               kvm_err("kvm: module already exists\n");
-               return -EEXIST;
-       }
-
-       return kvm_mips_emulation_init(&kvm_mips_callbacks);
+       return kvm_mips_emulation_init();
 }
 
 void kvm_arch_exit(void)
 {
-       kvm_mips_callbacks = NULL;
+
 }
 
 int kvm_arch_vcpu_ioctl_get_sregs(struct kvm_vcpu *vcpu,

diff --git a/arch/mips/kvm/vz.c b/arch/mips/kvm/vz.c
index c706f5890a05c6749ff13a4d0b68b7f541d85aa7..dafab003ea0df283cb862767770f2d3fac098880 100644 (file)
--- a/arch/mips/kvm/vz.c
+++ b/arch/mips/kvm/vz.c
@@ -3304,7 +3304,10 @@ static struct kvm_mips_callbacks kvm_vz_callbacks = {
        .vcpu_reenter = kvm_vz_vcpu_reenter,
 };
 
-int kvm_mips_emulation_init(struct kvm_mips_callbacks **install_callbacks)
+/* FIXME: Get rid of the callbacks now that trap-and-emulate is gone. */
+struct kvm_mips_callbacks *kvm_mips_callbacks = &kvm_vz_callbacks;
+
+int kvm_mips_emulation_init(void)
 {
        if (!cpu_has_vz)
                return -ENODEV;
@@ -3318,7 +3321,5 @@ int kvm_mips_emulation_init(struct kvm_mips_callbacks **install_callbacks)
                return -ENODEV;
 
        pr_info("Starting KVM with MIPS VZ extensions\n");
-
-       *install_callbacks = &kvm_vz_callbacks;
        return 0;
 }