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Do init_ucall() automatically during VM creation to kill two (three?) birds with one stone. First, initializing ucall immediately after VM creations allows forcing aarch64's MMIO ucall address to immediately follow memslot0. This is still somewhat fragile as tests could clobber the MMIO address with a new memslot, but it's safe-ish since tests have to be conversative when accounting for memslot0. And this can be hardened in the future by creating a read-only memslot for the MMIO page (KVM ARM exits with MMIO if the guest writes to a read-only memslot). Add a TODO to document that selftests can and should use a memslot for the ucall MMIO (doing so requires yet more rework because tests assumes thay can use all memslots except memslot0). Second, initializing ucall for all VMs prepares for making ucall initialization meaningful on all architectures. aarch64 is currently the only arch that needs to do any setup, but that will change in the future by switching to a pool-based implementation (instead of the current stack-based approach). Lastly, defining the ucall MMIO address from common code will simplify switching all architectures (except s390) to a common MMIO-based ucall implementation (if there's ever sufficient motivation to do so). Cc: Oliver Upton <oliver.upton@linux.dev> Reviewed-by: Andrew Jones <andrew.jones@linux.dev> Tested-by: Peter Gonda <pgonda@google.com> Signed-off-by: Sean Christopherson <seanjc@google.com> Link: https://lore.kernel.org/r/20221006003409.649993-4-seanjc@google.com
73 lines
1.8 KiB
C
73 lines
1.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* ucall support. A ucall is a "hypercall to userspace".
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*
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* Copyright (C) 2021 Western Digital Corporation or its affiliates.
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*/
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#include <linux/kvm.h>
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#include "kvm_util.h"
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#include "processor.h"
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void ucall_arch_init(struct kvm_vm *vm, vm_paddr_t mmio_gpa)
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{
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}
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void ucall_arch_uninit(struct kvm_vm *vm)
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{
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}
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struct sbiret sbi_ecall(int ext, int fid, unsigned long arg0,
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unsigned long arg1, unsigned long arg2,
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unsigned long arg3, unsigned long arg4,
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unsigned long arg5)
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{
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register uintptr_t a0 asm ("a0") = (uintptr_t)(arg0);
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register uintptr_t a1 asm ("a1") = (uintptr_t)(arg1);
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register uintptr_t a2 asm ("a2") = (uintptr_t)(arg2);
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register uintptr_t a3 asm ("a3") = (uintptr_t)(arg3);
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register uintptr_t a4 asm ("a4") = (uintptr_t)(arg4);
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register uintptr_t a5 asm ("a5") = (uintptr_t)(arg5);
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register uintptr_t a6 asm ("a6") = (uintptr_t)(fid);
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register uintptr_t a7 asm ("a7") = (uintptr_t)(ext);
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struct sbiret ret;
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asm volatile (
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"ecall"
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: "+r" (a0), "+r" (a1)
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: "r" (a2), "r" (a3), "r" (a4), "r" (a5), "r" (a6), "r" (a7)
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: "memory");
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ret.error = a0;
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ret.value = a1;
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return ret;
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}
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void ucall_arch_do_ucall(vm_vaddr_t uc)
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{
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sbi_ecall(KVM_RISCV_SELFTESTS_SBI_EXT,
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KVM_RISCV_SELFTESTS_SBI_UCALL,
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uc, 0, 0, 0, 0, 0);
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}
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void *ucall_arch_get_ucall(struct kvm_vcpu *vcpu)
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{
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struct kvm_run *run = vcpu->run;
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if (run->exit_reason == KVM_EXIT_RISCV_SBI &&
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run->riscv_sbi.extension_id == KVM_RISCV_SELFTESTS_SBI_EXT) {
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switch (run->riscv_sbi.function_id) {
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case KVM_RISCV_SELFTESTS_SBI_UCALL:
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return addr_gva2hva(vcpu->vm, run->riscv_sbi.args[0]);
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case KVM_RISCV_SELFTESTS_SBI_UNEXP:
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vcpu_dump(stderr, vcpu, 2);
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TEST_ASSERT(0, "Unexpected trap taken by guest");
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break;
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default:
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break;
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}
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}
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return NULL;
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}
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