lkml.org 
[lkml]   [2020]   [Mar]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 23/70] x86/sev-es: Add support for handling IOIO exceptions
    Date
    From: Tom Lendacky <thomas.lendacky@amd.com>

    Add support for decoding and handling #VC exceptions for IOIO events.

    Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
    [ jroedel@suse.de: Adapted code to #VC handling framework ]
    Co-developed-by: Joerg Roedel <jroedel@suse.de>
    Signed-off-by: Joerg Roedel <jroedel@suse.de>
    ---
    arch/x86/boot/compressed/sev-es.c | 32 +++++
    arch/x86/kernel/sev-es-shared.c | 202 ++++++++++++++++++++++++++++++
    2 files changed, 234 insertions(+)

    diff --git a/arch/x86/boot/compressed/sev-es.c b/arch/x86/boot/compressed/sev-es.c
    index 193c970a3379..ae5fbd371fd9 100644
    --- a/arch/x86/boot/compressed/sev-es.c
    +++ b/arch/x86/boot/compressed/sev-es.c
    @@ -18,6 +18,35 @@
    struct ghcb boot_ghcb_page __aligned(PAGE_SIZE);
    struct ghcb *boot_ghcb;

    +/*
    + * Copy a version of this function here - insn-eval.c can't be used in
    + * pre-decompression code.
    + */
    +static bool insn_rep_prefix(struct insn *insn)
    +{
    + int i;
    +
    + insn_get_prefixes(insn);
    +
    + for (i = 0; i < insn->prefixes.nbytes; i++) {
    + insn_byte_t p = insn->prefixes.bytes[i];
    +
    + if (p == 0xf2 || p == 0xf3)
    + return true;
    + }
    +
    + return false;
    +}
    +
    +/*
    + * Only a dummy for insn_get_seg_base() - Early boot-code is 64bit only and
    + * doesn't use segments.
    + */
    +static unsigned long insn_get_seg_base(struct pt_regs *regs, int seg_reg_idx)
    +{
    + return 0UL;
    +}
    +
    static inline u64 sev_es_rd_ghcb_msr(void)
    {
    unsigned long low, high;
    @@ -117,6 +146,9 @@ void boot_vc_handler(struct pt_regs *regs, unsigned long exit_code)
    goto finish;

    switch (exit_code) {
    + case SVM_EXIT_IOIO:
    + result = vc_handle_ioio(boot_ghcb, &ctxt);
    + break;
    default:
    result = ES_UNSUPPORTED;
    break;
    diff --git a/arch/x86/kernel/sev-es-shared.c b/arch/x86/kernel/sev-es-shared.c
    index f0947ea3c601..46fc5318d1d7 100644
    --- a/arch/x86/kernel/sev-es-shared.c
    +++ b/arch/x86/kernel/sev-es-shared.c
    @@ -205,3 +205,205 @@ static enum es_result vc_insn_string_write(struct es_em_ctxt *ctxt,

    return ret;
    }
    +
    +#define IOIO_TYPE_STR BIT(2)
    +#define IOIO_TYPE_IN 1
    +#define IOIO_TYPE_INS (IOIO_TYPE_IN | IOIO_TYPE_STR)
    +#define IOIO_TYPE_OUT 0
    +#define IOIO_TYPE_OUTS (IOIO_TYPE_OUT | IOIO_TYPE_STR)
    +
    +#define IOIO_REP BIT(3)
    +
    +#define IOIO_ADDR_64 BIT(9)
    +#define IOIO_ADDR_32 BIT(8)
    +#define IOIO_ADDR_16 BIT(7)
    +
    +#define IOIO_DATA_32 BIT(6)
    +#define IOIO_DATA_16 BIT(5)
    +#define IOIO_DATA_8 BIT(4)
    +
    +#define IOIO_SEG_ES (0 << 10)
    +#define IOIO_SEG_DS (3 << 10)
    +
    +static enum es_result vc_ioio_exitinfo(struct es_em_ctxt *ctxt, u64 *exitinfo)
    +{
    + struct insn *insn = &ctxt->insn;
    + *exitinfo = 0;
    +
    + switch (insn->opcode.bytes[0]) {
    + /* INS opcodes */
    + case 0x6c:
    + case 0x6d:
    + *exitinfo |= IOIO_TYPE_INS;
    + *exitinfo |= IOIO_SEG_ES;
    + *exitinfo |= (ctxt->regs->dx & 0xffff) << 16;
    + break;
    +
    + /* OUTS opcodes */
    + case 0x6e:
    + case 0x6f:
    + *exitinfo |= IOIO_TYPE_OUTS;
    + *exitinfo |= IOIO_SEG_DS;
    + *exitinfo |= (ctxt->regs->dx & 0xffff) << 16;
    + break;
    +
    + /* IN immediate opcodes */
    + case 0xe4:
    + case 0xe5:
    + *exitinfo |= IOIO_TYPE_IN;
    + *exitinfo |= insn->immediate.value << 16;
    + break;
    +
    + /* OUT immediate opcodes */
    + case 0xe6:
    + case 0xe7:
    + *exitinfo |= IOIO_TYPE_OUT;
    + *exitinfo |= insn->immediate.value << 16;
    + break;
    +
    + /* IN register opcodes */
    + case 0xec:
    + case 0xed:
    + *exitinfo |= IOIO_TYPE_IN;
    + *exitinfo |= (ctxt->regs->dx & 0xffff) << 16;
    + break;
    +
    + /* OUT register opcodes */
    + case 0xee:
    + case 0xef:
    + *exitinfo |= IOIO_TYPE_OUT;
    + *exitinfo |= (ctxt->regs->dx & 0xffff) << 16;
    + break;
    +
    + default:
    + return ES_DECODE_FAILED;
    + }
    +
    + switch (insn->opcode.bytes[0]) {
    + case 0x6c:
    + case 0x6e:
    + case 0xe4:
    + case 0xe6:
    + case 0xec:
    + case 0xee:
    + /* Single byte opcodes */
    + *exitinfo |= IOIO_DATA_8;
    + break;
    + default:
    + /* Length determined by instruction parsing */
    + *exitinfo |= (insn->opnd_bytes == 2) ? IOIO_DATA_16
    + : IOIO_DATA_32;
    + }
    + switch (insn->addr_bytes) {
    + case 2:
    + *exitinfo |= IOIO_ADDR_16;
    + break;
    + case 4:
    + *exitinfo |= IOIO_ADDR_32;
    + break;
    + case 8:
    + *exitinfo |= IOIO_ADDR_64;
    + break;
    + }
    +
    + if (insn_rep_prefix(insn))
    + *exitinfo |= IOIO_REP;
    +
    + return ES_OK;
    +}
    +
    +static enum es_result vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt)
    +{
    + struct pt_regs *regs = ctxt->regs;
    + u64 exit_info_1, exit_info_2;
    + enum es_result ret;
    +
    + ret = vc_ioio_exitinfo(ctxt, &exit_info_1);
    + if (ret != ES_OK)
    + return ret;
    +
    + if (exit_info_1 & IOIO_TYPE_STR) {
    + int df = (regs->flags & X86_EFLAGS_DF) ? -1 : 1;
    + 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 an 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 & IOIO_REP) ? regs->cx : 1;
    + exit_info_2 = min(op_count, ghcb_count);
    + exit_bytes = exit_info_2 * io_bytes;
    +
    + es_base = insn_get_seg_base(ctxt->regs, INAT_SEG_REG_ES);
    +
    + if (!(exit_info_1 & IOIO_TYPE_IN)) {
    + ret = vc_insn_string_read(ctxt,
    + (void *)(es_base + regs->si),
    + ghcb->shared_buffer, io_bytes,
    + exit_info_2, df);
    + if (ret)
    + return ret;
    + }
    +
    + 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;
    +
    + /* Everything went well, write back results */
    + if (exit_info_1 & IOIO_TYPE_IN) {
    + ret = vc_insn_string_write(ctxt,
    + (void *)(es_base + regs->di),
    + ghcb->shared_buffer, io_bytes,
    + exit_info_2, df);
    + if (ret)
    + return ret;
    +
    + if (df)
    + regs->di -= exit_bytes;
    + else
    + regs->di += exit_bytes;
    + } else {
    + if (df)
    + regs->si -= exit_bytes;
    + else
    + regs->si += exit_bytes;
    + }
    +
    + if (exit_info_1 & IOIO_REP)
    + regs->cx -= exit_info_2;
    +
    + ret = regs->cx ? ES_RETRY : ES_OK;
    +
    + } else {
    + int bits = (exit_info_1 & 0x70) >> 1;
    + u64 rax = 0;
    +
    + if (!(exit_info_1 & IOIO_TYPE_IN))
    + rax = lower_bits(regs->ax, bits);
    +
    + ghcb_set_rax(ghcb, rax);
    +
    + ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_IOIO, exit_info_1, 0);
    + if (ret != ES_OK)
    + return ret;
    +
    + if (exit_info_1 & IOIO_TYPE_IN) {
    + if (!ghcb_is_valid_rax(ghcb))
    + return ES_VMM_ERROR;
    + regs->ax = lower_bits(ghcb->save.rax, bits);
    + }
    + }
    +
    + return ret;
    +}
    --
    2.17.1
    \
     
     \ /
      Last update: 2020-03-19 10:19    [W:4.099 / U:0.320 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site