With VHE, the host never issues an HVC instruction to get into the
KVM code, as we can simply branch there.
Use runtime code patching to simplify things a bit.
Signed-off-by: Marc Zyngier <marc.zyng...@arm.com>
---
arch/arm64/kvm/hyp.S | 43 ++++++++++++++++++++++++++++++++++++-------
arch/arm64/kvm/vhe-macros.h | 36 ++++++++++++++++++++++++++++++++++++
2 files changed, 72 insertions(+), 7 deletions(-)
create mode 100644 arch/arm64/kvm/vhe-macros.h
diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S
index 17a8fb1..a65e053 100644
--- a/arch/arm64/kvm/hyp.S
+++ b/arch/arm64/kvm/hyp.S
@@ -30,6 +30,8 @@
#include <asm/kvm_mmu.h>
#include <asm/memory.h>
+#include "vhe-macros.h"
+
#define CPU_GP_REG_OFFSET(x) (CPU_GP_REGS + x)
#define CPU_XREG_OFFSET(x) CPU_GP_REG_OFFSET(CPU_USER_PT_REGS + 8*x)
#define CPU_SPSR_OFFSET(x) CPU_GP_REG_OFFSET(CPU_SPSR + 8*x)
@@ -39,6 +41,19 @@
.pushsection .hyp.text, "ax"
.align PAGE_SHIFT
+.macro do_el2_call
+ /*
+ * Shuffle the parameters before calling the function
+ * pointed to in x0. Assumes parameters in x[1,2,3],
+ * clobbers lr.
+ */
+ mov lr, x0
+ mov x0, x1
+ mov x1, x2
+ mov x2, x3
+ blr lr
+.endm
+
.macro save_common_regs
// x2: base address for cpu context
// x3: tmp register
@@ -1124,7 +1139,23 @@ __hyp_panic_str:
* arch/arm64/kernel/hyp_stub.S.
*/
ENTRY(kvm_call_hyp)
- hvc #0
+ /*
+ * NOP out the hvc/ret sequence on VHE, and fall through.
+ */
+ifnvhe hvc #0, nop
+ifnvhe ret, "push lr, xzr"
+
+ do_el2_call
+
+ /*
+ * We used to rely on having an exception return to get
+ * an implicit isb. In the E2H case, we don't have it anymore.
+ * rather than changing all the leaf functions, just do it here
+ * before returning to the rest of the kernel.
+ */
+ isb
+
+ pop lr, xzr
ret
ENDPROC(kvm_call_hyp)
@@ -1156,7 +1187,9 @@ el1_sync: // Guest
trapped into EL2
mrs x1, esr_el2
lsr x2, x1, #ESR_ELx_EC_SHIFT
- cmp x2, #ESR_ELx_EC_HVC64
+ // Ugly shortcut for VHE. We can do this early because the
+ // host cannot do an HVC.
+ifnvhe _S_(cmp x2, #ESR_ELx_EC_HVC64), "b el1_trap"
b.ne el1_trap
mrs x3, vttbr_el2 // If vttbr is valid, the 64bit
guest
@@ -1177,11 +1210,7 @@ el1_sync: //
Guest trapped into EL2
* Compute the function address in EL2, and shuffle the parameters.
*/
kern_hyp_va x0
- mov lr, x0
- mov x0, x1
- mov x1, x2
- mov x2, x3
- blr lr
+ do_el2_call
pop lr, xzr
2: eret
diff --git a/arch/arm64/kvm/vhe-macros.h b/arch/arm64/kvm/vhe-macros.h
new file mode 100644
index 0000000..da7f9da
--- /dev/null
+++ b/arch/arm64/kvm/vhe-macros.h
@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 2015 - ARM Ltd
+ * Author: Marc Zyngier <marc.zyng...@arm.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef __ARM64_VHE_MACROS_H__
+#define __ARM64_VHE_MACROS_H__
+
+#include <asm/alternative.h>
+#include <asm/cpufeature.h>
+
+#ifdef __ASSEMBLY__
+
+/* Hack to allow stringification of macros... */
+#define __S__(a,args...) __stringify(a, ##args)
+#define _S_(a,args...) __S__(a, args)
+
+.macro ifnvhe nonvhe vhe
+ alternative_insn "\nonvhe", "\vhe", ARM64_HAS_VIRT_HOST_EXTN
+.endm
+
+#endif
+
+#endif /*__ARM64_VHE_MACROS_H__ */
--
2.1.4
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