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Signed-off-by: Vasant Karasulli --- lib/x86/amd_sev_vc.c | 108 ++++++++++++++++++++++++++++++++++++++++++- 1 file changed, 106 insertions(+), 2 deletions(-) -- 2.34.1 diff --git a/lib/x86/amd_sev_vc.c b/lib/x86/amd_sev_vc.c index 0cdb9c06..77892edd 100644 --- a/lib/x86/amd_sev_vc.c +++ b/lib/x86/amd_sev_vc.c @@ -275,10 +275,46 @@ static enum es_result vc_ioio_exitinfo(struct es_em_ctxt *ctxt, u64 *exitinfo) return ES_OK; } +static enum es_result vc_insn_string_read(struct es_em_ctxt *ctxt, + void *src, unsigned char *buf, + unsigned int data_size, + unsigned int count, + bool backwards) +{ + int i, b = backwards ? -1 : 1; + + for (i = 0; i < count; i++) { + void *s = src + (i * data_size * b); + unsigned char *d = buf + (i * data_size); + + memcpy(d, s, data_size); + } + + return ES_OK; +} + +static enum es_result vc_insn_string_write(struct es_em_ctxt *ctxt, + void *dst, unsigned char *buf, + unsigned int data_size, + unsigned int count, + bool backwards) +{ + int i, s = backwards ? -1 : 1; + + for (i = 0; i < count; i++) { + void *d = dst + (i * data_size * s); + unsigned char *b = buf + (i * data_size); + + memcpy(d, b, data_size); + } + + return ES_OK; +} + static enum es_result vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt) { struct ex_regs *regs = ctxt->regs; - u64 exit_info_1; + u64 exit_info_1, exit_info_2; enum es_result ret; ret = vc_ioio_exitinfo(ctxt, &exit_info_1); @@ -286,7 +322,75 @@ static enum es_result vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt) return ret; if (exit_info_1 & SVM_IOIO_TYPE_STR) { - ret = ES_VMM_ERROR; + /* (REP) INS/OUTS */ + + bool df = ((regs->rflags & X86_EFLAGS_DF) == X86_EFLAGS_DF); + unsigned int io_bytes, exit_bytes; + unsigned int ghcb_count, op_count; + unsigned long es_base; + u64 sw_scratch; + + /* + * For the string variants with rep prefix the amount of in/out + * operations per #VC exception is limited so that the kernel + * has a chance to take interrupts and re-schedule while the + * instruction is emulated. + */ + io_bytes = (exit_info_1 >> 4) & 0x7; + ghcb_count = sizeof(ghcb->shared_buffer) / io_bytes; + + op_count = (exit_info_1 & SVM_IOIO_REP) ? regs->rcx : 1; + exit_info_2 = op_count < ghcb_count ? op_count : ghcb_count; + exit_bytes = exit_info_2 * io_bytes; + + es_base = 0; + + /* Read bytes of OUTS into the shared buffer */ + if (!(exit_info_1 & SVM_IOIO_TYPE_IN)) { + ret = vc_insn_string_read(ctxt, + (void *)(es_base + regs->rsi), + ghcb->shared_buffer, io_bytes, + exit_info_2, df); + if (ret) + return ret; + } + + /* + * Issue an VMGEXIT to the HV to consume the bytes from the + * shared buffer or to have it write them into the shared buffer + * depending on the instruction: OUTS or INS. + */ + sw_scratch = __pa(ghcb) + offsetof(struct ghcb, shared_buffer); + ghcb_set_sw_scratch(ghcb, sw_scratch); + ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_IOIO, + exit_info_1, exit_info_2); + if (ret != ES_OK) + return ret; + + /* Read bytes from shared buffer into the guest's destination. */ + if (exit_info_1 & SVM_IOIO_TYPE_IN) { + ret = vc_insn_string_write(ctxt, + (void *)(es_base + regs->rdi), + ghcb->shared_buffer, io_bytes, + exit_info_2, df); + if (ret) + return ret; + + if (df) + regs->rdi -= exit_bytes; + else + regs->rdi += exit_bytes; + } else { + if (df) + regs->rsi -= exit_bytes; + else + regs->rsi += exit_bytes; + } + + if (exit_info_1 & SVM_IOIO_REP) + regs->rcx -= exit_info_2; + + ret = regs->rcx ? ES_RETRY : ES_OK; } else { /* IN/OUT into/from rAX */