From 6ec6259d7084ed32e164c9f7b69049464dd90fa5 Mon Sep 17 00:00:00 2001 From: David Brazdil Date: Tue, 5 Jan 2021 18:05:38 +0000 Subject: KVM: arm64: Apply hyp relocations at runtime KVM nVHE code runs under a different VA mapping than the kernel, hence so far it avoided using absolute addressing because the VA in a constant pool is relocated by the linker to a kernel VA (see hyp_symbol_addr). Now the kernel has access to a list of positions that contain a kimg VA but will be accessed only in hyp execution context. These are generated by the gen-hyprel build-time tool and stored in .hyp.reloc. Add early boot pass over the entries and convert the kimg VAs to hyp VAs. Note that this requires for .hyp* ELF sections to be mapped read-write at that point. Signed-off-by: David Brazdil Signed-off-by: Marc Zyngier Link: https://lore.kernel.org/r/20210105180541.65031-6-dbrazdil@google.com --- arch/arm64/kvm/va_layout.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) (limited to 'arch/arm64/kvm/va_layout.c') diff --git a/arch/arm64/kvm/va_layout.c b/arch/arm64/kvm/va_layout.c index 70fcd6a12fe1..fee7dcd95d73 100644 --- a/arch/arm64/kvm/va_layout.c +++ b/arch/arm64/kvm/va_layout.c @@ -81,6 +81,34 @@ __init void kvm_compute_layout(void) init_hyp_physvirt_offset(); } +/* + * The .hyp.reloc ELF section contains a list of kimg positions that + * contains kimg VAs but will be accessed only in hyp execution context. + * Convert them to hyp VAs. See gen-hyprel.c for more details. + */ +__init void kvm_apply_hyp_relocations(void) +{ + int32_t *rel; + int32_t *begin = (int32_t *)__hyp_reloc_begin; + int32_t *end = (int32_t *)__hyp_reloc_end; + + for (rel = begin; rel < end; ++rel) { + uintptr_t *ptr, kimg_va; + + /* + * Each entry contains a 32-bit relative offset from itself + * to a kimg VA position. + */ + ptr = (uintptr_t *)lm_alias((char *)rel + *rel); + + /* Read the kimg VA value at the relocation address. */ + kimg_va = *ptr; + + /* Convert to hyp VA and store back to the relocation address. */ + *ptr = __early_kern_hyp_va((uintptr_t)lm_alias(kimg_va)); + } +} + static u32 compute_instruction(int n, u32 rd, u32 rn) { u32 insn = AARCH64_BREAK_FAULT; -- cgit v1.2.3