KVM/arm64 is so far unable to deal with function pointers, as the compiler will generate the kernel's runtime VA, and not the linear mapping address, meaning that kern_hyp_va() will give the wrong result.
We so far have been able to use PC-relative addressing, but that's not always easy to use, and prevents the implementation of things like the mapping of an index to a pointer. To allow this, provide a new helper that computes the required translation from the kernel image to the HYP VA space. Signed-off-by: Marc Zyngier <[email protected]> --- arch/arm64/include/asm/kvm_mmu.h | 18 ++++++++++++ arch/arm64/kvm/va_layout.c | 50 ++++++++++++++++++++++++++++++++ 2 files changed, 68 insertions(+) diff --git a/arch/arm64/include/asm/kvm_mmu.h b/arch/arm64/include/asm/kvm_mmu.h index 331394306cce..608c3a83e740 100644 --- a/arch/arm64/include/asm/kvm_mmu.h +++ b/arch/arm64/include/asm/kvm_mmu.h @@ -98,6 +98,24 @@ static __always_inline unsigned long __kern_hyp_va(unsigned long v) #define kern_hyp_va(v) ((typeof(v))(__kern_hyp_va((unsigned long)(v)))) +static __always_inline unsigned long __kimg_hyp_va(unsigned long v) +{ + unsigned long offset; + + asm volatile(ALTERNATIVE_CB("movz %0, #0\n" + "movk %0, #0, lsl #16\n" + "movk %0, #0, lsl #32\n" + "movk %0, #0, lsl #48\n", + kvm_update_kimg_phys_offset) + : "=r" (offset)); + + return __kern_hyp_va((v - offset) | PAGE_OFFSET); +} + +#define kimg_fn_hyp_va(v) ((typeof(*v))(__kimg_hyp_va((unsigned long)(v)))) + +#define kimg_fn_ptr(x) (typeof(x) **)(x) + /* * We currently support using a VM-specified IPA size. For backward * compatibility, the default IPA size is fixed to 40bits. diff --git a/arch/arm64/kvm/va_layout.c b/arch/arm64/kvm/va_layout.c index e0404bcab019..1d00d2cb93fd 100644 --- a/arch/arm64/kvm/va_layout.c +++ b/arch/arm64/kvm/va_layout.c @@ -11,6 +11,7 @@ #include <asm/debug-monitors.h> #include <asm/insn.h> #include <asm/kvm_mmu.h> +#include <asm/memory.h> /* * The LSB of the HYP VA tag @@ -201,3 +202,52 @@ void kvm_patch_vector_branch(struct alt_instr *alt, AARCH64_INSN_BRANCH_NOLINK); *updptr++ = cpu_to_le32(insn); } + +static void generate_mov_q(u64 val, __le32 *origptr, __le32 *updptr, int nr_inst) +{ + u32 insn, oinsn, rd; + + BUG_ON(nr_inst != 4); + + /* Compute target register */ + oinsn = le32_to_cpu(*origptr); + rd = aarch64_insn_decode_register(AARCH64_INSN_REGTYPE_RD, oinsn); + + /* movz rd, #(val & 0xffff) */ + insn = aarch64_insn_gen_movewide(rd, + (u16)val, + 0, + AARCH64_INSN_VARIANT_64BIT, + AARCH64_INSN_MOVEWIDE_ZERO); + *updptr++ = cpu_to_le32(insn); + + /* movk rd, #((val >> 16) & 0xffff), lsl #16 */ + insn = aarch64_insn_gen_movewide(rd, + (u16)(val >> 16), + 16, + AARCH64_INSN_VARIANT_64BIT, + AARCH64_INSN_MOVEWIDE_KEEP); + *updptr++ = cpu_to_le32(insn); + + /* movk rd, #((val >> 32) & 0xffff), lsl #32 */ + insn = aarch64_insn_gen_movewide(rd, + (u16)(val >> 32), + 32, + AARCH64_INSN_VARIANT_64BIT, + AARCH64_INSN_MOVEWIDE_KEEP); + *updptr++ = cpu_to_le32(insn); + + /* movk rd, #((val >> 48) & 0xffff), lsl #48 */ + insn = aarch64_insn_gen_movewide(rd, + (u16)(val >> 48), + 48, + AARCH64_INSN_VARIANT_64BIT, + AARCH64_INSN_MOVEWIDE_KEEP); + *updptr++ = cpu_to_le32(insn); +} + +void kvm_update_kimg_phys_offset(struct alt_instr *alt, + __le32 *origptr, __le32 *updptr, int nr_inst) +{ + generate_mov_q(kimage_voffset + PHYS_OFFSET, origptr, updptr, nr_inst); +} -- 2.28.0 _______________________________________________ kvmarm mailing list [email protected] https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
