Since the host is called from the hyp run loop, we can use that context to identify calls from the host rather than checking VTTBR_EL2, which will be used for the host's stage 2 in future.
Moving this to C also allows for more flexibiliy e.g. in applying policies, such as forbidding HVC_RESET_VECTORS, based on the current state of the hypervisor and removes the special casing for nVHE in the exception handler. Control over arch workaround 2 is made available to the host, the same as any other vcpu. Signed-off-by: Andrew Scull <[email protected]> --- arch/arm64/kvm/hyp/hyp-entry.S | 1 - arch/arm64/kvm/hyp/nvhe/host.S | 26 +-------------- arch/arm64/kvm/hyp/nvhe/hyp-init.S | 13 ++++++-- arch/arm64/kvm/hyp/nvhe/hyp-main.c | 51 +++++++++++++++++++++++++++++- 4 files changed, 62 insertions(+), 29 deletions(-) diff --git a/arch/arm64/kvm/hyp/hyp-entry.S b/arch/arm64/kvm/hyp/hyp-entry.S index b7a1ea221f6e..db54f84003ec 100644 --- a/arch/arm64/kvm/hyp/hyp-entry.S +++ b/arch/arm64/kvm/hyp/hyp-entry.S @@ -24,7 +24,6 @@ el1_sync: // Guest trapped into EL2 ccmp x0, #ESR_ELx_EC_HVC32, #4, ne b.ne el1_trap -el1_hvc_guest: /* * Fastest possible path for ARM_SMCCC_ARCH_WORKAROUND_1. * The workaround has already been applied on the host, diff --git a/arch/arm64/kvm/hyp/nvhe/host.S b/arch/arm64/kvm/hyp/nvhe/host.S index 40620c1c87b8..68d425b7bd62 100644 --- a/arch/arm64/kvm/hyp/nvhe/host.S +++ b/arch/arm64/kvm/hyp/nvhe/host.S @@ -95,31 +95,7 @@ SYM_FUNC_END(__hyp_do_panic) .macro valid_host_el1_sync_vect .align 7 - stp x0, x1, [sp, #-16]! - mrs x0, esr_el2 - lsr x0, x0, #ESR_ELx_EC_SHIFT - cmp x0, #ESR_ELx_EC_HVC64 - ldp x0, x1, [sp], #16 - b.ne __host_exit - - /* Check for a stub HVC call */ - cmp x0, #HVC_STUB_HCALL_NR - b.hs __host_exit - - /* - * Compute the idmap address of __kvm_handle_stub_hvc and - * jump there. Since we use kimage_voffset, do not use the - * HYP VA for __kvm_handle_stub_hvc, but the kernel VA instead - * (by loading it from the constant pool). - * - * Preserve x0-x4, which may contain stub parameters. - */ - ldr x5, =__kvm_handle_stub_hvc - ldr_l x6, kimage_voffset - - /* x5 = __pa(x5) */ - sub x5, x5, x6 - br x5 + b __host_exit .endm .macro invalid_host_el2_vect diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-init.S b/arch/arm64/kvm/hyp/nvhe/hyp-init.S index 47224dc62c51..40b5aa95c194 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-init.S +++ b/arch/arm64/kvm/hyp/nvhe/hyp-init.S @@ -16,6 +16,9 @@ #include <asm/sysreg.h> #include <asm/virt.h> +#include <asm/kvm_asm.h> +#include <asm/kvm_ptrauth.h> + .text .pushsection .hyp.idmap.text, "ax" @@ -138,6 +141,7 @@ SYM_CODE_START(__kvm_handle_stub_hvc) cmp x0, #HVC_SOFT_RESTART b.ne 1f +SYM_INNER_LABEL(__kvm_handle_stub_hvc_soft_restart, SYM_L_GLOBAL) /* This is where we're about to jump, staying at EL2 */ msr elr_el2, x1 mov x0, #(PSR_F_BIT | PSR_I_BIT | PSR_A_BIT | PSR_D_BIT | PSR_MODE_EL2h) @@ -150,8 +154,13 @@ SYM_CODE_START(__kvm_handle_stub_hvc) b reset 1: cmp x0, #HVC_RESET_VECTORS - b.ne 1f + b.ne 3f + b 2f + +SYM_INNER_LABEL(__kvm_handle_stub_hvc_reset_vectors, SYM_L_GLOBAL) + restore_callee_saved_regs x5 +2: /* * Set the HVC_RESET_VECTORS return code before entering the common * path so that we do not clobber x0-x2 in case we are coming via @@ -172,7 +181,7 @@ reset: msr vbar_el2, x5 eret -1: /* Bad stub call */ +3: /* Bad stub call */ mov_q x0, HVC_STUB_ERR eret diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c index 78d7afcefbb8..302333ea96eb 100644 --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c @@ -14,6 +14,52 @@ #include <kvm/arm_hypercalls.h> +typedef __noreturn unsigned long (*stub_hvc_handler_t) + (unsigned long, unsigned long, unsigned long, unsigned long, + unsigned long, struct kvm_cpu_context *); + +extern char __kvm_handle_stub_hvc_soft_restart[]; +extern char __kvm_handle_stub_hvc_reset_vectors[]; + +static void handle_stub_hvc(unsigned long func_id, + struct kvm_cpu_context *host_ctxt) +{ + char *stub_hvc_handler_kern_va; + stub_hvc_handler_t stub_hvc_handler; + + /* + * The handlers of the supported stub HVCs disable the MMU so they must + * be called in the idmap. We compute the idmap address by subtracting + * kimage_voffset from the kernel VA handler. + */ + switch (func_id) { + case HVC_SOFT_RESTART: + asm volatile("ldr %0, =%1" + : "=r" (stub_hvc_handler_kern_va) + : "S" (__kvm_handle_stub_hvc_soft_restart)); + break; + case HVC_RESET_VECTORS: + asm volatile("ldr %0, =%1" + : "=r" (stub_hvc_handler_kern_va) + : "S" (__kvm_handle_stub_hvc_reset_vectors)); + break; + default: + host_ctxt->regs.regs[0] = HVC_STUB_ERR; + return; + } + + stub_hvc_handler = (stub_hvc_handler_t) + (stub_hvc_handler_kern_va - kimage_voffset); + + /* Preserve x0-x4, which may contain stub parameters. */ + stub_hvc_handler(func_id, + host_ctxt->regs.regs[1], + host_ctxt->regs.regs[2], + host_ctxt->regs.regs[3], + host_ctxt->regs.regs[4], + host_ctxt); +} + static void handle_host_hcall(unsigned long func_id, struct kvm_cpu_context *host_ctxt) { @@ -118,5 +164,8 @@ void handle_trap(struct kvm_cpu_context *host_ctxt) { hyp_panic(); func_id = host_ctxt->regs.regs[0]; - handle_host_hcall(func_id, host_ctxt); + if (func_id < HVC_STUB_HCALL_NR) + handle_stub_hvc(func_id, host_ctxt); + else + handle_host_hcall(func_id, host_ctxt); } -- 2.28.0.220.ged08abb693-goog _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
