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x86/sev-es: Add support for handling IOIO exceptions
Add support for decoding and handling #VC exceptions for IOIO events. [ jroedel@suse.de: Adapted code to #VC handling framework ] Co-developed-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Borislav Petkov <bp@suse.de> Link: https://lkml.kernel.org/r/20200907131613.12703-26-joro@8bytes.org
This commit is contained in:
Tom Lendacky
Borislav Petkov
parent
69add17a7c
commit
25189d08e5
@ -24,6 +24,35 @@
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struct ghcb boot_ghcb_page __aligned(PAGE_SIZE);
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struct ghcb *boot_ghcb;
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/*
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* Copy a version of this function here - insn-eval.c can't be used in
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* pre-decompression code.
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*/
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static bool insn_has_rep_prefix(struct insn *insn)
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{
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int i;
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insn_get_prefixes(insn);
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for (i = 0; i < insn->prefixes.nbytes; i++) {
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insn_byte_t p = insn->prefixes.bytes[i];
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if (p == 0xf2 || p == 0xf3)
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return true;
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}
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return false;
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}
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/*
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* Only a dummy for insn_get_seg_base() - Early boot-code is 64bit only and
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* doesn't use segments.
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*/
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static unsigned long insn_get_seg_base(struct pt_regs *regs, int seg_reg_idx)
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{
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return 0UL;
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}
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static inline u64 sev_es_rd_ghcb_msr(void)
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{
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unsigned long low, high;
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@ -151,6 +180,9 @@ void do_boot_stage2_vc(struct pt_regs *regs, unsigned long exit_code)
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goto finish;
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switch (exit_code) {
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case SVM_EXIT_IOIO:
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result = vc_handle_ioio(boot_ghcb, &ctxt);
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break;
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default:
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result = ES_UNSUPPORTED;
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break;
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@ -218,3 +218,217 @@ static enum es_result vc_insn_string_write(struct es_em_ctxt *ctxt,
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return ret;
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}
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#define IOIO_TYPE_STR BIT(2)
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#define IOIO_TYPE_IN 1
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#define IOIO_TYPE_INS (IOIO_TYPE_IN | IOIO_TYPE_STR)
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#define IOIO_TYPE_OUT 0
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#define IOIO_TYPE_OUTS (IOIO_TYPE_OUT | IOIO_TYPE_STR)
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#define IOIO_REP BIT(3)
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#define IOIO_ADDR_64 BIT(9)
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#define IOIO_ADDR_32 BIT(8)
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#define IOIO_ADDR_16 BIT(7)
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#define IOIO_DATA_32 BIT(6)
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#define IOIO_DATA_16 BIT(5)
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#define IOIO_DATA_8 BIT(4)
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#define IOIO_SEG_ES (0 << 10)
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#define IOIO_SEG_DS (3 << 10)
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static enum es_result vc_ioio_exitinfo(struct es_em_ctxt *ctxt, u64 *exitinfo)
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{
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struct insn *insn = &ctxt->insn;
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*exitinfo = 0;
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switch (insn->opcode.bytes[0]) {
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/* INS opcodes */
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case 0x6c:
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case 0x6d:
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*exitinfo |= IOIO_TYPE_INS;
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*exitinfo |= IOIO_SEG_ES;
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*exitinfo |= (ctxt->regs->dx & 0xffff) << 16;
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break;
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/* OUTS opcodes */
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case 0x6e:
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case 0x6f:
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*exitinfo |= IOIO_TYPE_OUTS;
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*exitinfo |= IOIO_SEG_DS;
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*exitinfo |= (ctxt->regs->dx & 0xffff) << 16;
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break;
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/* IN immediate opcodes */
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case 0xe4:
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case 0xe5:
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*exitinfo |= IOIO_TYPE_IN;
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*exitinfo |= (u64)insn->immediate.value << 16;
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break;
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/* OUT immediate opcodes */
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case 0xe6:
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case 0xe7:
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*exitinfo |= IOIO_TYPE_OUT;
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*exitinfo |= (u64)insn->immediate.value << 16;
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break;
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/* IN register opcodes */
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case 0xec:
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case 0xed:
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*exitinfo |= IOIO_TYPE_IN;
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*exitinfo |= (ctxt->regs->dx & 0xffff) << 16;
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break;
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/* OUT register opcodes */
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case 0xee:
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case 0xef:
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*exitinfo |= IOIO_TYPE_OUT;
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*exitinfo |= (ctxt->regs->dx & 0xffff) << 16;
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break;
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default:
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return ES_DECODE_FAILED;
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}
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switch (insn->opcode.bytes[0]) {
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case 0x6c:
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case 0x6e:
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case 0xe4:
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case 0xe6:
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case 0xec:
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case 0xee:
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/* Single byte opcodes */
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*exitinfo |= IOIO_DATA_8;
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break;
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default:
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/* Length determined by instruction parsing */
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*exitinfo |= (insn->opnd_bytes == 2) ? IOIO_DATA_16
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: IOIO_DATA_32;
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}
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switch (insn->addr_bytes) {
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case 2:
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*exitinfo |= IOIO_ADDR_16;
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break;
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case 4:
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*exitinfo |= IOIO_ADDR_32;
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break;
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case 8:
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*exitinfo |= IOIO_ADDR_64;
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break;
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}
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if (insn_has_rep_prefix(insn))
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*exitinfo |= IOIO_REP;
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return ES_OK;
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}
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static enum es_result vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
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{
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struct pt_regs *regs = ctxt->regs;
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u64 exit_info_1, exit_info_2;
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enum es_result ret;
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ret = vc_ioio_exitinfo(ctxt, &exit_info_1);
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if (ret != ES_OK)
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return ret;
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if (exit_info_1 & IOIO_TYPE_STR) {
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/* (REP) INS/OUTS */
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bool df = ((regs->flags & X86_EFLAGS_DF) == X86_EFLAGS_DF);
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unsigned int io_bytes, exit_bytes;
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unsigned int ghcb_count, op_count;
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unsigned long es_base;
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u64 sw_scratch;
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/*
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* For the string variants with rep prefix the amount of in/out
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* operations per #VC exception is limited so that the kernel
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* has a chance to take interrupts and re-schedule while the
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* instruction is emulated.
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*/
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io_bytes = (exit_info_1 >> 4) & 0x7;
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ghcb_count = sizeof(ghcb->shared_buffer) / io_bytes;
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op_count = (exit_info_1 & IOIO_REP) ? regs->cx : 1;
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exit_info_2 = min(op_count, ghcb_count);
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exit_bytes = exit_info_2 * io_bytes;
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es_base = insn_get_seg_base(ctxt->regs, INAT_SEG_REG_ES);
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/* Read bytes of OUTS into the shared buffer */
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if (!(exit_info_1 & IOIO_TYPE_IN)) {
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ret = vc_insn_string_read(ctxt,
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(void *)(es_base + regs->si),
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ghcb->shared_buffer, io_bytes,
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exit_info_2, df);
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if (ret)
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return ret;
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}
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/*
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* Issue an VMGEXIT to the HV to consume the bytes from the
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* shared buffer or to have it write them into the shared buffer
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* depending on the instruction: OUTS or INS.
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*/
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sw_scratch = __pa(ghcb) + offsetof(struct ghcb, shared_buffer);
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ghcb_set_sw_scratch(ghcb, sw_scratch);
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ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_IOIO,
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exit_info_1, exit_info_2);
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if (ret != ES_OK)
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return ret;
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/* Read bytes from shared buffer into the guest's destination. */
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if (exit_info_1 & IOIO_TYPE_IN) {
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ret = vc_insn_string_write(ctxt,
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(void *)(es_base + regs->di),
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ghcb->shared_buffer, io_bytes,
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exit_info_2, df);
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if (ret)
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return ret;
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if (df)
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regs->di -= exit_bytes;
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else
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regs->di += exit_bytes;
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} else {
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if (df)
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regs->si -= exit_bytes;
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else
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regs->si += exit_bytes;
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}
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if (exit_info_1 & IOIO_REP)
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regs->cx -= exit_info_2;
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ret = regs->cx ? ES_RETRY : ES_OK;
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} else {
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/* IN/OUT into/from rAX */
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int bits = (exit_info_1 & 0x70) >> 1;
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u64 rax = 0;
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if (!(exit_info_1 & IOIO_TYPE_IN))
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rax = lower_bits(regs->ax, bits);
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ghcb_set_rax(ghcb, rax);
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ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_IOIO, exit_info_1, 0);
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if (ret != ES_OK)
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return ret;
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if (exit_info_1 & IOIO_TYPE_IN) {
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if (!ghcb_rax_is_valid(ghcb))
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return ES_VMM_ERROR;
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regs->ax = lower_bits(ghcb->save.rax, bits);
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}
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}
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return ret;
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}
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