KVM: MMU: hypercall based pte updates and TLB flushes

Hypercall based pte updates are faster than faults, and also allow use
of the lazy MMU mode to batch operations.

Don't report the feature if two dimensional paging is enabled.

[avi:
 - one mmu_op hypercall instead of one per op
 - allow 64-bit gpa on hypercall
 - don't pass host errors (-ENOMEM) to guest]

[akpm: warning fix on i386]

Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Avi Kivity <avi@qumranet.com>

4 files changed, 38 insertions, 1 deletions

diff --git a/include/asm-x86/kvm_host.h b/include/asm-x86/kvm_host.h
index 99d31f5ed9ff..772ba95f0a0e 100644
--- a/include/asm-x86/kvm_host.h
+++ b/include/asm-x86/kvm_host.h
@@ -434,6 +434,10 @@ int load_pdptrs(struct kvm_vcpu *vcpu, unsigned long cr3);
 
 int __emulator_write_phys(struct kvm_vcpu *vcpu, gpa_t gpa,
                           const void *val, int bytes);
+int kvm_pv_mmu_op(struct kvm_vcpu *vcpu, unsigned long bytes,
+                  gpa_t addr, unsigned long *ret);
+
+extern bool tdp_enabled;
 
 enum emulation_result {
         EMULATE_DONE,       /* no further processing */
diff --git a/include/asm-x86/kvm_para.h b/include/asm-x86/kvm_para.h
index ed5df3a54aab..509845942070 100644
--- a/include/asm-x86/kvm_para.h
+++ b/include/asm-x86/kvm_para.h
@@ -12,10 +12,39 @@
 #define KVM_CPUID_FEATURES      0x40000001
 #define KVM_FEATURE_CLOCKSOURCE         0
 #define KVM_FEATURE_NOP_IO_DELAY        1
+#define KVM_FEATURE_MMU_OP              2
 
 #define MSR_KVM_WALL_CLOCK  0x11
 #define MSR_KVM_SYSTEM_TIME 0x12
 
+#define KVM_MAX_MMU_OP_BATCH           32
+
+/* Operations for KVM_HC_MMU_OP */
+#define KVM_MMU_OP_WRITE_PTE            1
+#define KVM_MMU_OP_FLUSH_TLB            2
+#define KVM_MMU_OP_RELEASE_PT           3
+
+/* Payload for KVM_HC_MMU_OP */
+struct kvm_mmu_op_header {
+        __u32 op;
+        __u32 pad;
+};
+
+struct kvm_mmu_op_write_pte {
+        struct kvm_mmu_op_header header;
+        __u64 pte_phys;
+        __u64 pte_val;
+};
+
+struct kvm_mmu_op_flush_tlb {
+        struct kvm_mmu_op_header header;
+};
+
+struct kvm_mmu_op_release_pt {
+        struct kvm_mmu_op_header header;
+        __u64 pt_phys;
+};
+
 #ifdef __KERNEL__
 #include <asm/processor.h>
 
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 76f09474be98..c1b502a50a01 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -238,6 +238,7 @@ struct kvm_vapic_addr {
 #define KVM_CAP_NR_MEMSLOTS 10   /* returns max memory slots per vm */
 #define KVM_CAP_PIT 11
 #define KVM_CAP_NOP_IO_DELAY 12
+#define KVM_CAP_PV_MMU 13
 
 /*
  * ioctls for VM fds
diff --git a/include/linux/kvm_para.h b/include/linux/kvm_para.h
index 9c462c91a6b1..3ddce03766ca 100644
--- a/include/linux/kvm_para.h
+++ b/include/linux/kvm_para.h
@@ -11,8 +11,11 @@
 
 /* Return values for hypercalls */
 #define KVM_ENOSYS              1000
+#define KVM_EFAULT              EFAULT
+#define KVM_E2BIG               E2BIG
 
-#define KVM_HC_VAPIC_POLL_IRQ            1
+#define KVM_HC_VAPIC_POLL_IRQ           1
+#define KVM_HC_MMU_OP                   2
 
 /*
  * hypercalls use architecture specific