From: Tom Lendacky <thomas.lendacky@xxxxxxx> Add handler for VC exceptions caused by MMIO intercepts. These intercepts come along as nested page faults on pages with reserved bits set. Signed-off-by: Tom Lendacky <thomas.lendacky@xxxxxxx> [ jroedel@xxxxxxx: Adapt to VC handling framework ] Co-developed-by: Joerg Roedel <jroedel@xxxxxxx> Signed-off-by: Joerg Roedel <jroedel@xxxxxxx> Link: https://lore.kernel.org/r/20200724160336.5435-52-joro@xxxxxxxxxx --- arch/x86/include/uapi/asm/svm.h | 5 + arch/x86/kernel/sev-es.c | 220 ++++++++++++++++++++++++++++++++ 2 files changed, 225 insertions(+) diff --git a/arch/x86/include/uapi/asm/svm.h b/arch/x86/include/uapi/asm/svm.h index c68d1618c9b0..8f36ae021a7f 100644 --- a/arch/x86/include/uapi/asm/svm.h +++ b/arch/x86/include/uapi/asm/svm.h @@ -81,6 +81,11 @@ #define SVM_EXIT_AVIC_INCOMPLETE_IPI 0x401 #define SVM_EXIT_AVIC_UNACCELERATED_ACCESS 0x402 +/* SEV-ES software-defined VMGEXIT events */ +#define SVM_VMGEXIT_MMIO_READ 0x80000001 +#define SVM_VMGEXIT_MMIO_WRITE 0x80000002 +#define SVM_VMGEXIT_UNSUPPORTED_EVENT 0x8000ffff + #define SVM_EXIT_ERR -1 #define SVM_EXIT_REASONS \ diff --git a/arch/x86/kernel/sev-es.c b/arch/x86/kernel/sev-es.c index 1493e8cf14f2..fa1fa55fd8e3 100644 --- a/arch/x86/kernel/sev-es.c +++ b/arch/x86/kernel/sev-es.c @@ -364,6 +364,37 @@ static enum es_result vc_read_mem(struct es_em_ctxt *ctxt, return ES_EXCEPTION; } +static bool vc_slow_virt_to_phys(struct ghcb *ghcb, struct es_em_ctxt *ctxt, + unsigned long vaddr, phys_addr_t *paddr) +{ + unsigned long va = (unsigned long)vaddr; + unsigned int level; + phys_addr_t pa; + pgd_t *pgd; + pte_t *pte; + + pgd = __va(read_cr3_pa()); + pgd = &pgd[pgd_index(va)]; + pte = lookup_address_in_pgd(pgd, va, &level); + if (!pte) { + ctxt->fi.vector = X86_TRAP_PF; + ctxt->fi.cr2 = vaddr; + ctxt->fi.error_code = 0; + + if (user_mode(ctxt->regs)) + ctxt->fi.error_code |= X86_PF_USER; + + return false; + } + + pa = (phys_addr_t)pte_pfn(*pte) << PAGE_SHIFT; + pa |= va & ~page_level_mask(level); + + *paddr = pa; + + return true; +} + /* Include code shared with pre-decompression boot stage */ #include "sev-es-shared.c" @@ -449,6 +480,192 @@ static void __init vc_early_forward_exception(struct es_em_ctxt *ctxt) do_early_exception(ctxt->regs, trapnr); } +static long *vc_insn_get_reg(struct es_em_ctxt *ctxt) +{ + long *reg_array; + int offset; + + reg_array = (long *)ctxt->regs; + offset = insn_get_modrm_reg_off(&ctxt->insn, ctxt->regs); + + if (offset < 0) + return NULL; + + offset /= sizeof(long); + + return reg_array + offset; +} + +static enum es_result vc_do_mmio(struct ghcb *ghcb, struct es_em_ctxt *ctxt, + unsigned int bytes, bool read) +{ + u64 exit_code, exit_info_1, exit_info_2; + unsigned long ghcb_pa = __pa(ghcb); + phys_addr_t paddr; + void __user *ref; + + ref = insn_get_addr_ref(&ctxt->insn, ctxt->regs); + if (ref == (void __user *)-1L) + return ES_UNSUPPORTED; + + exit_code = read ? SVM_VMGEXIT_MMIO_READ : SVM_VMGEXIT_MMIO_WRITE; + + if (!vc_slow_virt_to_phys(ghcb, ctxt, (unsigned long)ref, &paddr)) { + if (!read) + ctxt->fi.error_code |= X86_PF_WRITE; + + return ES_EXCEPTION; + } + + exit_info_1 = paddr; + exit_info_2 = bytes; /* Can never be greater than 8 */ + + ghcb->save.sw_scratch = ghcb_pa + offsetof(struct ghcb, shared_buffer); + + return sev_es_ghcb_hv_call(ghcb, ctxt, exit_code, exit_info_1, exit_info_2); +} + +static enum es_result vc_handle_mmio_twobyte_ops(struct ghcb *ghcb, + struct es_em_ctxt *ctxt) +{ + struct insn *insn = &ctxt->insn; + unsigned int bytes = 0; + enum es_result ret; + int sign_byte; + long *reg_data; + + switch (insn->opcode.bytes[1]) { + /* MMIO Read w/ zero-extension */ + case 0xb6: + bytes = 1; + fallthrough; + case 0xb7: + if (!bytes) + bytes = 2; + + ret = vc_do_mmio(ghcb, ctxt, bytes, true); + if (ret) + break; + + /* Zero extend based on operand size */ + reg_data = vc_insn_get_reg(ctxt); + if (!reg_data) + return ES_DECODE_FAILED; + + memset(reg_data, 0, insn->opnd_bytes); + + memcpy(reg_data, ghcb->shared_buffer, bytes); + break; + + /* MMIO Read w/ sign-extension */ + case 0xbe: + bytes = 1; + fallthrough; + case 0xbf: + if (!bytes) + bytes = 2; + + ret = vc_do_mmio(ghcb, ctxt, bytes, true); + if (ret) + break; + + /* Sign extend based on operand size */ + reg_data = vc_insn_get_reg(ctxt); + if (!reg_data) + return ES_DECODE_FAILED; + + if (bytes == 1) { + u8 *val = (u8 *)ghcb->shared_buffer; + + sign_byte = (*val & 0x80) ? 0xff : 0x00; + } else { + u16 *val = (u16 *)ghcb->shared_buffer; + + sign_byte = (*val & 0x8000) ? 0xff : 0x00; + } + memset(reg_data, sign_byte, insn->opnd_bytes); + + memcpy(reg_data, ghcb->shared_buffer, bytes); + break; + + default: + ret = ES_UNSUPPORTED; + } + + return ret; +} + +static enum es_result vc_handle_mmio(struct ghcb *ghcb, + struct es_em_ctxt *ctxt) +{ + struct insn *insn = &ctxt->insn; + unsigned int bytes = 0; + enum es_result ret; + long *reg_data; + + switch (insn->opcode.bytes[0]) { + /* MMIO Write */ + case 0x88: + bytes = 1; + fallthrough; + case 0x89: + if (!bytes) + bytes = insn->opnd_bytes; + + reg_data = vc_insn_get_reg(ctxt); + if (!reg_data) + return ES_DECODE_FAILED; + + memcpy(ghcb->shared_buffer, reg_data, bytes); + + ret = vc_do_mmio(ghcb, ctxt, bytes, false); + break; + + case 0xc6: + bytes = 1; + fallthrough; + case 0xc7: + if (!bytes) + bytes = insn->opnd_bytes; + + memcpy(ghcb->shared_buffer, insn->immediate1.bytes, bytes); + + ret = vc_do_mmio(ghcb, ctxt, bytes, false); + break; + + /* MMIO Read */ + case 0x8a: + bytes = 1; + fallthrough; + case 0x8b: + if (!bytes) + bytes = insn->opnd_bytes; + + ret = vc_do_mmio(ghcb, ctxt, bytes, true); + if (ret) + break; + + reg_data = vc_insn_get_reg(ctxt); + if (!reg_data) + return ES_DECODE_FAILED; + + if (bytes == 4) + *reg_data = 0; /* Zero-extend for 32-bit operation */ + + memcpy(reg_data, ghcb->shared_buffer, bytes); + break; + + /* Two-Byte Opcodes */ + case 0x0f: + ret = vc_handle_mmio_twobyte_ops(ghcb, ctxt); + break; + default: + ret = ES_UNSUPPORTED; + } + + return ret; +} + static enum es_result vc_handle_exitcode(struct es_em_ctxt *ctxt, struct ghcb *ghcb, unsigned long exit_code) @@ -462,6 +679,9 @@ static enum es_result vc_handle_exitcode(struct es_em_ctxt *ctxt, case SVM_EXIT_IOIO: result = vc_handle_ioio(ghcb, ctxt); break; + case SVM_EXIT_NPF: + result = vc_handle_mmio(ghcb, ctxt); + break; default: /* * Unexpected #VC exception -- 2.28.0
