KVM/MIPS32: Binary patching of select privileged instructions.
Currently, the following instructions are translated:
- CACHE (indexed)
- CACHE (va based): translated to a SYNCI, overkill on D-CACHE operations,
but still much faster than a trap.
- mfc0/mtc0: the virtual COP0 registers for the guest are implemented as
2-D array.
[COP#][SEL] and this is mapped into the guest kernel address space @ VA 0x0.
mfc0/mtc0 operations are transformed to load/stores.
Signed-off-by: Sanjay Lal <sanjayl@kymasys.com>
Cc: kvm@vger.kernel.org
Cc: linux-mips@linux-mips.org
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/kvm/kvm_mips_dyntrans.c b/arch/mips/kvm/kvm_mips_dyntrans.c
new file mode 100644
index 0000000..96528e2
--- /dev/null
+++ b/arch/mips/kvm/kvm_mips_dyntrans.c
@@ -0,0 +1,149 @@
+/*
+* 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.
+*
+* KVM/MIPS: Binary Patching for privileged instructions, reduces traps.
+*
+* Copyright (C) 2012 MIPS Technologies, Inc. All rights reserved.
+* Authors: Sanjay Lal <sanjayl@kymasys.com>
+*/
+
+#include <linux/errno.h>
+#include <linux/err.h>
+#include <linux/kvm_host.h>
+#include <linux/module.h>
+#include <linux/vmalloc.h>
+#include <linux/fs.h>
+#include <linux/bootmem.h>
+
+#include "kvm_mips_comm.h"
+
+#define SYNCI_TEMPLATE 0x041f0000
+#define SYNCI_BASE(x) (((x) >> 21) & 0x1f)
+#define SYNCI_OFFSET ((x) & 0xffff)
+
+#define LW_TEMPLATE 0x8c000000
+#define CLEAR_TEMPLATE 0x00000020
+#define SW_TEMPLATE 0xac000000
+
+int
+kvm_mips_trans_cache_index(uint32_t inst, uint32_t *opc,
+ struct kvm_vcpu *vcpu)
+{
+ int result = 0;
+ unsigned long kseg0_opc;
+ uint32_t synci_inst = 0x0;
+
+ /* Replace the CACHE instruction, with a NOP */
+ kseg0_opc =
+ CKSEG0ADDR(kvm_mips_translate_guest_kseg0_to_hpa
+ (vcpu, (unsigned long) opc));
+ memcpy((void *)kseg0_opc, (void *)&synci_inst, sizeof(uint32_t));
+ mips32_SyncICache(kseg0_opc, 32);
+
+ return result;
+}
+
+/*
+ * Address based CACHE instructions are transformed into synci(s). A little heavy
+ * for just D-cache invalidates, but avoids an expensive trap
+ */
+int
+kvm_mips_trans_cache_va(uint32_t inst, uint32_t *opc,
+ struct kvm_vcpu *vcpu)
+{
+ int result = 0;
+ unsigned long kseg0_opc;
+ uint32_t synci_inst = SYNCI_TEMPLATE, base, offset;
+
+ base = (inst >> 21) & 0x1f;
+ offset = inst & 0xffff;
+ synci_inst |= (base << 21);
+ synci_inst |= offset;
+
+ kseg0_opc =
+ CKSEG0ADDR(kvm_mips_translate_guest_kseg0_to_hpa
+ (vcpu, (unsigned long) opc));
+ memcpy((void *)kseg0_opc, (void *)&synci_inst, sizeof(uint32_t));
+ mips32_SyncICache(kseg0_opc, 32);
+
+ return result;
+}
+
+int
+kvm_mips_trans_mfc0(uint32_t inst, uint32_t *opc, struct kvm_vcpu *vcpu)
+{
+ int32_t rt, rd, sel;
+ uint32_t mfc0_inst;
+ unsigned long kseg0_opc, flags;
+
+ rt = (inst >> 16) & 0x1f;
+ rd = (inst >> 11) & 0x1f;
+ sel = inst & 0x7;
+
+ if ((rd == MIPS_CP0_ERRCTL) && (sel == 0)) {
+ mfc0_inst = CLEAR_TEMPLATE;
+ mfc0_inst |= ((rt & 0x1f) << 16);
+ } else {
+ mfc0_inst = LW_TEMPLATE;
+ mfc0_inst |= ((rt & 0x1f) << 16);
+ mfc0_inst |=
+ offsetof(struct mips_coproc,
+ reg[rd][sel]) + offsetof(struct kvm_mips_commpage,
+ cop0);
+ }
+
+ if (KVM_GUEST_KSEGX(opc) == KVM_GUEST_KSEG0) {
+ kseg0_opc =
+ CKSEG0ADDR(kvm_mips_translate_guest_kseg0_to_hpa
+ (vcpu, (unsigned long) opc));
+ memcpy((void *)kseg0_opc, (void *)&mfc0_inst, sizeof(uint32_t));
+ mips32_SyncICache(kseg0_opc, 32);
+ } else if (KVM_GUEST_KSEGX((unsigned long) opc) == KVM_GUEST_KSEG23) {
+ local_irq_save(flags);
+ memcpy((void *)opc, (void *)&mfc0_inst, sizeof(uint32_t));
+ mips32_SyncICache((unsigned long) opc, 32);
+ local_irq_restore(flags);
+ } else {
+ kvm_err("%s: Invalid address: %p\n", __func__, opc);
+ return -EFAULT;
+ }
+
+ return 0;
+}
+
+int
+kvm_mips_trans_mtc0(uint32_t inst, uint32_t *opc, struct kvm_vcpu *vcpu)
+{
+ int32_t rt, rd, sel;
+ uint32_t mtc0_inst = SW_TEMPLATE;
+ unsigned long kseg0_opc, flags;
+
+ rt = (inst >> 16) & 0x1f;
+ rd = (inst >> 11) & 0x1f;
+ sel = inst & 0x7;
+
+ mtc0_inst |= ((rt & 0x1f) << 16);
+ mtc0_inst |=
+ offsetof(struct mips_coproc,
+ reg[rd][sel]) + offsetof(struct kvm_mips_commpage, cop0);
+
+ if (KVM_GUEST_KSEGX(opc) == KVM_GUEST_KSEG0) {
+ kseg0_opc =
+ CKSEG0ADDR(kvm_mips_translate_guest_kseg0_to_hpa
+ (vcpu, (unsigned long) opc));
+ memcpy((void *)kseg0_opc, (void *)&mtc0_inst, sizeof(uint32_t));
+ mips32_SyncICache(kseg0_opc, 32);
+ } else if (KVM_GUEST_KSEGX((unsigned long) opc) == KVM_GUEST_KSEG23) {
+ local_irq_save(flags);
+ memcpy((void *)opc, (void *)&mtc0_inst, sizeof(uint32_t));
+ mips32_SyncICache((unsigned long) opc, 32);
+ local_irq_restore(flags);
+ } else {
+ kvm_err("%s: Invalid address: %p\n", __func__, opc);
+ return -EFAULT;
+ }
+
+ return 0;
+}