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Fri, 20 Mar 2020 14:03:18 -0700 (PDT) Date: Fri, 20 Mar 2020 14:03:17 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Joerg Roedel cc: x86@kernel.org, hpa@zytor.com, Andy Lutomirski , Dave Hansen , Peter Zijlstra , Thomas Hellstrom , Jiri Slaby , Dan Williams , Tom Lendacky , Juergen Gross , Kees Cook , linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, Joerg Roedel Subject: Re: [PATCH 23/70] x86/sev-es: Add support for handling IOIO exceptions In-Reply-To: <20200319091407.1481-24-joro@8bytes.org> Message-ID: References: <20200319091407.1481-1-joro@8bytes.org> <20200319091407.1481-24-joro@8bytes.org> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 19 Mar 2020, Joerg Roedel wrote: > From: Tom Lendacky > > Add support for decoding and handling #VC exceptions for IOIO events. > > Signed-off-by: Tom Lendacky > [ jroedel@suse.de: Adapted code to #VC handling framework ] > Co-developed-by: Joerg Roedel > Signed-off-by: Joerg Roedel > --- > 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); The last argument to vc_insn_string_read() is "bool backwards" which in this case it appears will always be true? > + 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 > >