KVM: Move x86's version of struct kvm_mmu_memory_cache to common code

Move x86's 'struct kvm_mmu_memory_cache' to common code in anticipation
of moving the entire x86 implementation code to common KVM and reusing
it for arm64 and MIPS.  Add a new architecture specific asm/kvm_types.h
to control the existence and parameters of the struct.  The new header
is needed to avoid a chicken-and-egg problem with asm/kvm_host.h as all
architectures define instances of the struct in their vCPU structs.

Add an asm-generic version of kvm_types.h to avoid having empty files on
PPC and s390 in the long term, and for arm64 and mips in the short term.

Suggested-by: Christoffer Dall <christoffer.dall@arm.com>
Reviewed-by: Ben Gardon <bgardon@google.com>
Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Message-Id: <20200703023545.8771-15-sean.j.christopherson@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

diff --git a/arch/arm64/include/asm/Kbuild b/arch/arm64/include/asm/Kbuild
index ff9cbb6312128ada86abaa827fe07d02ed29e378..35a68155cd0e7f0df57759b013540d60c921ff6c 100644 (file)
--- a/arch/arm64/include/asm/Kbuild
+++ b/arch/arm64/include/asm/Kbuild
@@ -1,5 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 generic-y += early_ioremap.h
+generic-y += kvm_types.h
 generic-y += local64.h
 generic-y += mcs_spinlock.h
 generic-y += qrwlock.h

diff --git a/arch/mips/include/asm/Kbuild b/arch/mips/include/asm/Kbuild
index 8643d313890e7740d8035c9d5b16e344bd130a3b..397e6d24d2abef1fe811911e062502d8e6c474e2 100644 (file)
--- a/arch/mips/include/asm/Kbuild
+++ b/arch/mips/include/asm/Kbuild
@@ -5,6 +5,7 @@ generated-y += syscall_table_64_n32.h
 generated-y += syscall_table_64_n64.h
 generated-y += syscall_table_64_o32.h
 generic-y += export.h
+generic-y += kvm_types.h
 generic-y += local64.h
 generic-y += mcs_spinlock.h
 generic-y += parport.h

diff --git a/arch/powerpc/include/asm/Kbuild b/arch/powerpc/include/asm/Kbuild
index dadbcf3a0b1e77a2e62d2586c95302af24e5421e..2d444d09b5533e87d21724c0046def909fa3c0d0 100644 (file)
--- a/arch/powerpc/include/asm/Kbuild
+++ b/arch/powerpc/include/asm/Kbuild
@@ -4,6 +4,7 @@ generated-y += syscall_table_64.h
 generated-y += syscall_table_c32.h
 generated-y += syscall_table_spu.h
 generic-y += export.h
+generic-y += kvm_types.h
 generic-y += local64.h
 generic-y += mcs_spinlock.h
 generic-y += vtime.h

diff --git a/arch/s390/include/asm/Kbuild b/arch/s390/include/asm/Kbuild
index 83f6e85de7bc3495de367c56d6cf7df5ab4358d4..319efa0e6d024fecd1e503c9d722079ce1db213e 100644 (file)
--- a/arch/s390/include/asm/Kbuild
+++ b/arch/s390/include/asm/Kbuild
@@ -6,5 +6,6 @@ generated-y += unistd_nr.h
 
 generic-y += asm-offsets.h
 generic-y += export.h
+generic-y += kvm_types.h
 generic-y += local64.h
 generic-y += mcs_spinlock.h

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 9d41eb5a8453c690c81c78383f134a24b9b744a3..5aaef036627f488b93b757809e386600a8763757 100644 (file)
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -193,8 +193,6 @@ struct x86_exception;
 enum x86_intercept;
 enum x86_intercept_stage;
 
-#define KVM_NR_MEM_OBJS 40
-
 #define KVM_NR_DB_REGS 4
 
 #define DR6_BD         (1 << 13)
@@ -245,17 +243,6 @@ enum x86_intercept_stage;
 
 struct kvm_kernel_irq_routing_entry;
 
-/*
- * We don't want allocation failures within the mmu code, so we preallocate
- * enough memory for a single page fault in a cache.
- */
-struct kvm_mmu_memory_cache {
-       int nobjs;
-       gfp_t gfp_zero;
-       struct kmem_cache *kmem_cache;
-       void *objects[KVM_NR_MEM_OBJS];
-};
-
 /*
  * the pages used as guest page table on soft mmu are tracked by
  * kvm_memory_slot.arch.gfn_track which is 16 bits, so the role bits used

diff --git a/arch/x86/include/asm/kvm_types.h b/arch/x86/include/asm/kvm_types.h
new file mode 100644 (file)
index 0000000..08f1b57
--- /dev/null
+++ b/arch/x86/include/asm/kvm_types.h
@@ -0,0 +1,7 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_X86_KVM_TYPES_H
+#define _ASM_X86_KVM_TYPES_H
+
+#define KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE 40
+
+#endif /* _ASM_X86_KVM_TYPES_H */

diff --git a/include/asm-generic/kvm_types.h b/include/asm-generic/kvm_types.h
new file mode 100644 (file)
index 0000000..2a82daf
--- /dev/null
+++ b/include/asm-generic/kvm_types.h
@@ -0,0 +1,5 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_GENERIC_KVM_TYPES_H
+#define _ASM_GENERIC_KVM_TYPES_H
+
+#endif

diff --git a/include/linux/kvm_types.h b/include/linux/kvm_types.h
index 68e84cf42a3f94f2bcb6bf1b35d494f34ddeedad..a7580f69dda02e681228785c5c3cfa49b207d88c 100644 (file)
--- a/include/linux/kvm_types.h
+++ b/include/linux/kvm_types.h
@@ -20,6 +20,8 @@ enum kvm_mr_change;
 
 #include <linux/types.h>
 
+#include <asm/kvm_types.h>
+
 /*
  * Address types:
  *
@@ -58,4 +60,21 @@ struct gfn_to_pfn_cache {
        bool dirty;
 };
 
+#ifdef KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE
+/*
+ * Memory caches are used to preallocate memory ahead of various MMU flows,
+ * e.g. page fault handlers.  Gracefully handling allocation failures deep in
+ * MMU flows is problematic, as is triggering reclaim, I/O, etc... while
+ * holding MMU locks.  Note, these caches act more like prefetch buffers than
+ * classical caches, i.e. objects are not returned to the cache on being freed.
+ */
+struct kvm_mmu_memory_cache {
+       int nobjs;
+       gfp_t gfp_zero;
+       struct kmem_cache *kmem_cache;
+       void *objects[KVM_ARCH_NR_OBJS_PER_MEMORY_CACHE];
+};
+#endif
+
+
 #endif /* __KVM_TYPES_H__ */