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.zyngier@xxxxxxx> --- 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.zyngier@xxxxxxx> + * + * 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 -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
