The existing arm64 hcall implementations are limited in that they only allow for two distinct hcalls; with the x0 register either zero or not zero. Also, the API of the hyp-stub exception vector routines and the KVM exception vector routines differ; hyp-stub uses a non-zero value in x0 to implement __hyp_set_vectors, whereas KVM uses it to implement kvm_call_hyp. To allow for additional hcalls to be defined and to make the arm64 hcall API more consistent across exception vector routines, change the hcall implementations to use the 16 bit immediate value of the HVC instruction to specify the hcall type. Define three new preprocessor macros HVC_CALL_HYP, HVC_GET_VECTORS, and HVC_SET_VECTORS to be used as hcall type specifiers and convert the existing __hyp_get_vectors(), __hyp_set_vectors() and kvm_call_hyp() routines to use these new macros when executing an HVC call. Also, change the corresponding hyp-stub and KVM el1_sync exception vector routines to use these new macros. Signed-off-by: Geoff Levand <geoff at infradead.org> --- arch/arm64/include/asm/virt.h | 27 +++++++++++++++++++++++++++ arch/arm64/kernel/hyp-stub.S | 32 +++++++++++++++++++++----------- arch/arm64/kvm/hyp.S | 16 +++++++++------- 3 files changed, 57 insertions(+), 18 deletions(-) diff --git a/arch/arm64/include/asm/virt.h b/arch/arm64/include/asm/virt.h index 7a5df52..eb10368 100644 --- a/arch/arm64/include/asm/virt.h +++ b/arch/arm64/include/asm/virt.h @@ -18,6 +18,33 @@ #ifndef __ASM__VIRT_H #define __ASM__VIRT_H +/* + * The arm64 hcall implementation uses the ISS field of the ESR_EL2 register to + * specify the hcall type. The exception handlers are allowed to use registers + * x17 and x18 in their implementation. Any routine issuing an hcall must not + * expect these registers to be preserved. + */ + +/* + * HVC_CALL_HYP - Execute a hyp routine. + */ + +#define HVC_CALL_HYP 0 + +/* + * HVC_GET_VECTORS - Return the value of the vbar_el2 register. + */ + +#define HVC_GET_VECTORS 1 + +/* + * HVC_SET_VECTORS - Set the value of the vbar_el2 register. + * + * @x0: Physical address of the new vector table. + */ + +#define HVC_SET_VECTORS 2 + #define BOOT_CPU_MODE_EL1 (0xe11) #define BOOT_CPU_MODE_EL2 (0xe12) diff --git a/arch/arm64/kernel/hyp-stub.S b/arch/arm64/kernel/hyp-stub.S index a272f33..017ab519 100644 --- a/arch/arm64/kernel/hyp-stub.S +++ b/arch/arm64/kernel/hyp-stub.S @@ -22,6 +22,7 @@ #include <linux/irqchip/arm-gic-v3.h> #include <asm/assembler.h> +#include <asm/kvm_arm.h> #include <asm/ptrace.h> #include <asm/virt.h> @@ -53,14 +54,22 @@ ENDPROC(__hyp_stub_vectors) .align 11 el1_sync: - mrs x1, esr_el2 - lsr x1, x1, #26 - cmp x1, #0x16 + mrs x18, esr_el2 + lsr x17, x18, #ESR_ELx_EC_SHIFT + and x18, x18, #ESR_ELx_ISS_MASK + + cmp x17, #ESR_ELx_EC_HVC64 b.ne 2f // Not an HVC trap - cbz x0, 1f - msr vbar_el2, x0 // Set vbar_el2 + + cmp x18, #HVC_GET_VECTORS + b.ne 1f + mrs x0, vbar_el2 b 2f -1: mrs x0, vbar_el2 // Return vbar_el2 + +1: cmp x18, #HVC_SET_VECTORS + b.ne 2f + msr vbar_el2, x0 + 2: eret ENDPROC(el1_sync) @@ -100,11 +109,12 @@ ENDPROC(\label) * initialisation entry point. */ -ENTRY(__hyp_get_vectors) - mov x0, xzr - // fall through ENTRY(__hyp_set_vectors) - hvc #0 + hvc #HVC_SET_VECTORS ret -ENDPROC(__hyp_get_vectors) ENDPROC(__hyp_set_vectors) + +ENTRY(__hyp_get_vectors) + hvc #HVC_GET_VECTORS + ret +ENDPROC(__hyp_get_vectors) diff --git a/arch/arm64/kvm/hyp.S b/arch/arm64/kvm/hyp.S index 86c2898..15b1ef9 100644 --- a/arch/arm64/kvm/hyp.S +++ b/arch/arm64/kvm/hyp.S @@ -29,6 +29,7 @@ #include <asm/kvm_asm.h> #include <asm/kvm_mmu.h> #include <asm/memory.h> +#include <asm/virt.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) @@ -936,12 +937,9 @@ __hyp_panic_str: * in Hyp mode (see init_hyp_mode in arch/arm/kvm/arm.c). Return values are * passed in r0 and r1. * - * A function pointer with a value of 0 has a special meaning, and is - * used to implement __hyp_get_vectors in the same way as in - * arch/arm64/kernel/hyp_stub.S. */ ENTRY(kvm_call_hyp) - hvc #0 + hvc #HVC_CALL_HYP ret ENDPROC(kvm_call_hyp) @@ -972,6 +970,7 @@ el1_sync: // Guest trapped into EL2 mrs x1, esr_el2 lsr x2, x1, #ESR_ELx_EC_SHIFT + and x0, x1, #ESR_ELx_ISS_MASK cmp x2, #ESR_ELx_EC_HVC64 b.ne el1_trap @@ -980,15 +979,18 @@ el1_sync: // Guest trapped into EL2 cbnz x3, el1_trap // called HVC /* Here, we're pretty sure the host called HVC. */ + mov x18, x0 pop x2, x3 pop x0, x1 - /* Check for __hyp_get_vectors */ - cbnz x0, 1f + cmp x18, #HVC_GET_VECTORS + b.ne 1f mrs x0, vbar_el2 b 2f -1: push lr, xzr +1: /* Default to HVC_CALL_HYP. */ + + push lr, xzr /* * Compute the function address in EL2, and shuffle the parameters. -- 2.5.0
