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But the fact that it supports both interfaces > means that the GHCB page based logic is pulled into the early startup > code where PA to VA conversions are problematic, given that it runs from > the 1:1 mapping of memory. > > So keep snp_cpuid() itself in the startup code, but factor out the > hypervisor calls via a callback, so that the GHCB page handling can be > moved out. > > Code refactoring only - no functional change intended. > > Signed-off-by: Ard Biesheuvel > --- > arch/x86/boot/startup/sev-shared.c | 64 ++++---------------- > arch/x86/coco/sev/vc-shared.c | 49 ++++++++++++++- > arch/x86/include/asm/sev.h | 3 +- > 3 files changed, 63 insertions(+), 53 deletions(-) > > diff --git a/arch/x86/boot/startup/sev-shared.c b/arch/x86/boot/startup/sev-shared.c > index 7a706db87b93..992abfa50508 100644 > --- a/arch/x86/boot/startup/sev-shared.c > +++ b/arch/x86/boot/startup/sev-shared.c > @@ -319,7 +319,7 @@ static int __sev_cpuid_hv(u32 fn, int reg_idx, u32 *reg) > return 0; > } > > -static int __sev_cpuid_hv_msr(struct cpuid_leaf *leaf) > +static int __sev_cpuid_msr_prot(struct cpuid_leaf *leaf) Not sure the renaming makes it read any easier or say anything more. It does add extra changes to the diff that have to be read through, though, so I don't think it is beneficial. > { > int ret; > > @@ -342,44 +342,7 @@ static int __sev_cpuid_hv_msr(struct cpuid_leaf *leaf) > return ret; > } > > -static int __sev_cpuid_hv_ghcb(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf) > -{ > - u32 cr4 = native_read_cr4(); > - int ret; > - > - ghcb_set_rax(ghcb, leaf->fn); > - ghcb_set_rcx(ghcb, leaf->subfn); > - > - if (cr4 & X86_CR4_OSXSAVE) > - /* Safe to read xcr0 */ > - ghcb_set_xcr0(ghcb, xgetbv(XCR_XFEATURE_ENABLED_MASK)); > - else > - /* xgetbv will cause #UD - use reset value for xcr0 */ > - ghcb_set_xcr0(ghcb, 1); > - > - ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_CPUID, 0, 0); > - if (ret != ES_OK) > - return ret; > - > - if (!(ghcb_rax_is_valid(ghcb) && > - ghcb_rbx_is_valid(ghcb) && > - ghcb_rcx_is_valid(ghcb) && > - ghcb_rdx_is_valid(ghcb))) > - return ES_VMM_ERROR; > > - leaf->eax = ghcb->save.rax; > - leaf->ebx = ghcb->save.rbx; > - leaf->ecx = ghcb->save.rcx; > - leaf->edx = ghcb->save.rdx; > - > - return ES_OK; > -} > - > -static int sev_cpuid_hv(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf) > -{ > - return ghcb ? __sev_cpuid_hv_ghcb(ghcb, ctxt, leaf) > - : __sev_cpuid_hv_msr(leaf); > -} > > /* > * This may be called early while still running on the initial identity > @@ -484,21 +447,20 @@ snp_cpuid_get_validated_func(struct cpuid_leaf *leaf) > return false; > } > > -static void snp_cpuid_hv(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf) > +static void snp_cpuid_msr_prot(void *ctx, struct cpuid_leaf *leaf) > { > - if (sev_cpuid_hv(ghcb, ctxt, leaf)) > + if (__sev_cpuid_msr_prot(leaf)) > sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_CPUID_HV); > } > > -static int __head > -snp_cpuid_postprocess(struct ghcb *ghcb, struct es_em_ctxt *ctxt, > - struct cpuid_leaf *leaf) > +static int __head snp_cpuid_postprocess(void (*cpuid)(void *ctx, struct cpuid_leaf *), > + void *ctx, struct cpuid_leaf *leaf) > { > struct cpuid_leaf leaf_hv = *leaf; > > switch (leaf->fn) { > case 0x1: > - snp_cpuid_hv(ghcb, ctxt, &leaf_hv); > + cpuid(ctx, &leaf_hv); Maybe rename this parameter to snp_cpuid or snp_cpuid_fn or similar, because it can be very confusing to see "cpuid" on its own like this. > > /* initial APIC ID */ > leaf->ebx = (leaf_hv.ebx & GENMASK(31, 24)) | (leaf->ebx & GENMASK(23, 0)); > @@ -517,7 +479,7 @@ snp_cpuid_postprocess(struct ghcb *ghcb, struct es_em_ctxt *ctxt, > break; > case 0xB: > leaf_hv.subfn = 0; > - snp_cpuid_hv(ghcb, ctxt, &leaf_hv); > + cpuid(ctx, &leaf_hv); > > /* extended APIC ID */ > leaf->edx = leaf_hv.edx; > @@ -565,7 +527,7 @@ snp_cpuid_postprocess(struct ghcb *ghcb, struct es_em_ctxt *ctxt, > } > break; > case 0x8000001E: > - snp_cpuid_hv(ghcb, ctxt, &leaf_hv); > + cpuid(ctx, &leaf_hv); > > /* extended APIC ID */ > leaf->eax = leaf_hv.eax; > @@ -586,8 +548,8 @@ snp_cpuid_postprocess(struct ghcb *ghcb, struct es_em_ctxt *ctxt, > * Returns -EOPNOTSUPP if feature not enabled. Any other non-zero return value > * should be treated as fatal by caller. > */ > -int __head > -snp_cpuid(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf) > +int __head snp_cpuid(void (*cpuid)(void *ctx, struct cpuid_leaf *), void *ctx, > + struct cpuid_leaf *leaf) > { > const struct snp_cpuid_table *cpuid_table = snp_cpuid_get_table(); > > @@ -621,7 +583,7 @@ snp_cpuid(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf) > return 0; > } > > - return snp_cpuid_postprocess(ghcb, ctxt, leaf); > + return snp_cpuid_postprocess(cpuid, ctx, leaf); > } > > /* > @@ -648,14 +610,14 @@ void __head do_vc_no_ghcb(struct pt_regs *regs, unsigned long exit_code) > leaf.fn = fn; > leaf.subfn = subfn; > > - ret = snp_cpuid(NULL, NULL, &leaf); > + ret = snp_cpuid(snp_cpuid_msr_prot, NULL, &leaf); > if (!ret) > goto cpuid_done; > > if (ret != -EOPNOTSUPP) > goto fail; > > - if (__sev_cpuid_hv_msr(&leaf)) > + if (__sev_cpuid_msr_prot(&leaf)) > goto fail; > > cpuid_done: > diff --git a/arch/x86/coco/sev/vc-shared.c b/arch/x86/coco/sev/vc-shared.c > index 2c0ab0fdc060..776cb90be530 100644 > --- a/arch/x86/coco/sev/vc-shared.c > +++ b/arch/x86/coco/sev/vc-shared.c > @@ -409,15 +409,62 @@ static enum es_result vc_handle_ioio(struct ghcb *ghcb, struct es_em_ctxt *ctxt) > return ret; > } > > +static int __sev_cpuid_ghcb_prot(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf) Ditto here and below, keeping the __sev_cpuid_hv_ghcb() / sev_cpuid_hv_ghcb() name would be best. Thanks, Tom > +{ > + u32 cr4 = native_read_cr4(); > + int ret; > + > + ghcb_set_rax(ghcb, leaf->fn); > + ghcb_set_rcx(ghcb, leaf->subfn); > + > + if (cr4 & X86_CR4_OSXSAVE) > + /* Safe to read xcr0 */ > + ghcb_set_xcr0(ghcb, xgetbv(XCR_XFEATURE_ENABLED_MASK)); > + else > + /* xgetbv will cause #UD - use reset value for xcr0 */ > + ghcb_set_xcr0(ghcb, 1); > + > + ret = sev_es_ghcb_hv_call(ghcb, ctxt, SVM_EXIT_CPUID, 0, 0); > + if (ret != ES_OK) > + return ret; > + > + if (!(ghcb_rax_is_valid(ghcb) && > + ghcb_rbx_is_valid(ghcb) && > + ghcb_rcx_is_valid(ghcb) && > + ghcb_rdx_is_valid(ghcb))) > + return ES_VMM_ERROR; > + > + leaf->eax = ghcb->save.rax; > + leaf->ebx = ghcb->save.rbx; > + leaf->ecx = ghcb->save.rcx; > + leaf->edx = ghcb->save.rdx; > + > + return ES_OK; > +} > + > +struct cpuid_ctx { > + struct ghcb *ghcb; > + struct es_em_ctxt *ctxt; > +}; > + > +static void snp_cpuid_ghcb_prot(void *p, struct cpuid_leaf *leaf) > +{ > + struct cpuid_ctx *ctx = p; > + > + if (__sev_cpuid_ghcb_prot(ctx->ghcb, ctx->ctxt, leaf)) > + sev_es_terminate(SEV_TERM_SET_LINUX, GHCB_TERM_CPUID_HV); > +} > + > static int vc_handle_cpuid_snp(struct ghcb *ghcb, struct es_em_ctxt *ctxt) > { > + struct cpuid_ctx ctx = { ghcb, ctxt }; > struct pt_regs *regs = ctxt->regs; > struct cpuid_leaf leaf; > int ret; > > leaf.fn = regs->ax; > leaf.subfn = regs->cx; > - ret = snp_cpuid(ghcb, ctxt, &leaf); > + ret = snp_cpuid(snp_cpuid_ghcb_prot, &ctx, &leaf); > if (!ret) { > regs->ax = leaf.eax; > regs->bx = leaf.ebx; > diff --git a/arch/x86/include/asm/sev.h b/arch/x86/include/asm/sev.h > index 89075ff19afa..2cabf617de3c 100644 > --- a/arch/x86/include/asm/sev.h > +++ b/arch/x86/include/asm/sev.h > @@ -552,7 +552,8 @@ struct cpuid_leaf { > u32 edx; > }; > > -int snp_cpuid(struct ghcb *ghcb, struct es_em_ctxt *ctxt, struct cpuid_leaf *leaf); > +int snp_cpuid(void (*cpuid_hv)(void *ctx, struct cpuid_leaf *), > + void *ctx, struct cpuid_leaf *leaf); > > void __noreturn sev_es_terminate(unsigned int set, unsigned int reason); > enum es_result sev_es_ghcb_hv_call(struct ghcb *ghcb,