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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 09/13] Nested Virtualization: svm specific implementation
Hi,
At 18:43 +0000 on 12 Nov (1289587425), Christoph Egger wrote:
> +static int nsvm_vmrun_permissionmap(struct vcpu *v)
> +{
> + struct arch_svm_struct *arch_svm = &v->arch.hvm_svm;
> + struct nestedsvm *svm = &vcpu_nestedsvm(v);
> + struct vmcb_struct *ns_vmcb = vcpu_nestedhvm(v).nv_vmcx;
> + struct vmcb_struct *host_vmcb = arch_svm->vmcb;
> + unsigned long *ns_msrpm_ptr;
> + unsigned int i;
> + enum hvm_copy_result ret;
> +
> + ns_msrpm_ptr = (unsigned long *)svm->ns_cached_msrpm;
> +
> + ret = hvm_copy_from_guest_phys(svm->ns_cached_msrpm,
> + ns_vmcb->msrpm_base_pa, MSRPM_SIZE);
> + if (ret != HVMCOPY_okay) {
> + gdprintk(XENLOG_ERR, "hvm_copy_from_guest_phys msrpm %u\n", ret);
> + return 1;
> + }
> +
> + /* Skip io bitmap merge since hvm_io_bitmap has all bits set but
> + * 0x80 and 0xed.
> + */
What if the L1 hypervisor wants to intercept port 0x80 or port 0xed?
> + /* v->arch.hvm_svm.msrpm has type unsigned long, thus
> + * BYTES_PER_LONG.
> + */
> + for (i = 0; i < MSRPM_SIZE / BYTES_PER_LONG; i++)
> + svm->ns_merged_msrpm[i] = arch_svm->msrpm[i] | ns_msrpm_ptr[i];
> +
> + host_vmcb->iopm_base_pa =
> + (uint64_t)virt_to_maddr(hvm_io_bitmap);
> + host_vmcb->msrpm_base_pa =
> + (uint64_t)virt_to_maddr(svm->ns_merged_msrpm);
> +
> + return 0;
> +}
> +
> +static int nsvm_vmcb_prepare4vmrun(struct vcpu *v, struct cpu_user_regs
> *regs)
> +{
> + struct nestedsvm *svm = &vcpu_nestedsvm(v);
> + struct vmcb_struct *ns_vmcb = vcpu_nestedhvm(v).nv_vmcx;
> + struct vmcb_struct *host_vmcb = v->arch.hvm_svm.vmcb;
> + int rc;
> +
> + /* Enable nested guest intercepts */
> + svm->ns_cr_intercepts = ns_vmcb->cr_intercepts;
> + svm->ns_dr_intercepts = ns_vmcb->dr_intercepts;
> + svm->ns_exception_intercepts = ns_vmcb->exception_intercepts;
> + svm->ns_general1_intercepts = ns_vmcb->general1_intercepts;
> + svm->ns_general2_intercepts = ns_vmcb->general2_intercepts;
> +
> + host_vmcb->cr_intercepts |= ns_vmcb->cr_intercepts;
> + host_vmcb->dr_intercepts |= ns_vmcb->dr_intercepts;
> + host_vmcb->exception_intercepts |= ns_vmcb->exception_intercepts;
> + host_vmcb->general1_intercepts |= ns_vmcb->general1_intercepts;
> + host_vmcb->general2_intercepts |= ns_vmcb->general2_intercepts;
> +
> + /* Nested Pause Filter */
> + if (ns_vmcb->general1_intercepts & GENERAL1_INTERCEPT_PAUSE)
> + host_vmcb->pause_filter_count =
> + min(ns_vmcb->pause_filter_count, host_vmcb->pause_filter_count);
> + else
> + host_vmcb->pause_filter_count = SVM_PAUSEFILTER_INIT;
Why ignore the L0 count if the L1 doesn't intercept PAUSE?
> +
> + /* Nested IO permission bitmaps */
> + rc = nsvm_vmrun_permissionmap(v);
> + if (rc)
> + return rc;
> +
> + /* TSC offset */
> + hvm_set_guest_tsc(v, host_vmcb->tsc_offset + ns_vmcb->tsc_offset);
hvm_set_guest_tsc takes an absolute value, not an offset. ITYM to call
the hvm_funcs pointer directly.
> +
> + /* ASID */
> + hvm_asid_flush_vcpu(v);
> + /* host_vmcb->guest_asid = ns_vmcb->guest_asid; */
> +
> + /* TLB control */
> + host_vmcb->tlb_control |= ns_vmcb->tlb_control;
> +
> + /* Virtual Interrupts */
> + host_vmcb->vintr = ns_vmcb->vintr;
> + host_vmcb->vintr.fields.intr_masking = 1;
> +
> + /* Shadow Mode */
> + host_vmcb->interrupt_shadow = ns_vmcb->interrupt_shadow;
> +
> + /* Exit codes */
> + host_vmcb->exitcode = ns_vmcb->exitcode;
> + host_vmcb->exitinfo1 = ns_vmcb->exitinfo1;
> + host_vmcb->exitinfo2 = ns_vmcb->exitinfo2;
> + host_vmcb->exitintinfo = ns_vmcb->exitintinfo;
> +
> + /* Pending Interrupts */
> + host_vmcb->eventinj = ns_vmcb->eventinj;
> +
> + /* LBR virtualization */
> + svm->ns_lbr_control = ns_vmcb->lbr_control;
> + host_vmcb->lbr_control.bytes |= ns_vmcb->lbr_control.bytes;
> +
> + /* NextRIP */
> + host_vmcb->nextrip = ns_vmcb->nextrip;
> +
> + /*
> + * VMCB Save State Area
> + */
> +
> + /* Segments */
> + host_vmcb->es = ns_vmcb->es;
> + host_vmcb->cs = ns_vmcb->cs;
> + host_vmcb->ss = ns_vmcb->ss;
> + host_vmcb->ds = ns_vmcb->ds;
> + host_vmcb->gdtr = ns_vmcb->gdtr;
> + host_vmcb->idtr = ns_vmcb->idtr;
> +
> + /* CPL */
> + host_vmcb->cpl = ns_vmcb->cpl;
> +
> + /* EFER */
> + v->arch.hvm_vcpu.guest_efer = ns_vmcb->efer;
> + rc = hvm_set_efer(ns_vmcb->efer);
> + if (rc != X86EMUL_OKAY)
> + gdprintk(XENLOG_ERR, "hvm_set_efer failed, rc: %u\n", rc);
> +
> + /* CR4 */
> + v->arch.hvm_vcpu.guest_cr[4] = ns_vmcb->cr4;
> + rc = hvm_set_cr4(ns_vmcb->cr4);
> + if (rc != X86EMUL_OKAY)
> + gdprintk(XENLOG_ERR, "hvm_set_cr4 failed, rc: %u\n", rc);
> +
> + /* CR0 */
> + v->arch.hvm_vcpu.guest_cr[0] = ns_vmcb->cr0;
> + rc = hvm_set_cr0(ns_vmcb->cr0);
> + if (rc != X86EMUL_OKAY)
> + gdprintk(XENLOG_ERR, "hvm_set_cr0 failed, rc: %u\n", rc);
> +
> + /* CR2 */
> + v->arch.hvm_vcpu.guest_cr[2] = ns_vmcb->cr2;
> + hvm_update_guest_cr(v, 2);
> +
> + /* Nested paging mode */
> + if (nestedhvm_paging_mode_hap(v)) {
> + /* host nested paging + guest nested paging. */
> +
> + /* hvm_set_cr3() below sets v->arch.hvm_vcpu.guest_cr[3] for us. */
> + rc = hvm_set_cr3(ns_vmcb->cr3);
> + if (rc != X86EMUL_OKAY)
> + gdprintk(XENLOG_ERR, "hvm_set_cr3 failed, rc: %u\n", rc);
> + } else if (paging_mode_hap(v->domain)) {
> + /* host nested paging + guest shadow paging. */
> + host_vmcb->np_enable = 1;
> + /* Keep h_cr3 as it is. */
> + /* Guest shadow paging: Must intercept pagefaults. */
> + host_vmcb->exception_intercepts |= (1U << TRAP_page_fault);
No - it's the L1 hypervisor's job to intercep #PF if it wants to use
shadow paging. We shouldn't special-case it here.
> + /* hvm_set_cr3() below sets v->arch.hvm_vcpu.guest_cr[3] for us. */
> + rc = hvm_set_cr3(ns_vmcb->cr3);
> + if (rc != X86EMUL_OKAY)
> + gdprintk(XENLOG_ERR, "hvm_set_cr3 failed, rc: %u\n", rc);
> + } else {
> + /* host shadow paging + guest shadow paging. */
> + host_vmcb->np_enable = 0;
> + host_vmcb->h_cr3 = 0x0;
> +
> + /* TODO: Once shadow-shadow paging is in place come back to here
> + * and set host_vmcb->cr3 to the shadowed shadow table.
> + */
> + }
> +
> + /* DRn */
> + host_vmcb->dr7 = ns_vmcb->dr7;
> + host_vmcb->dr6 = ns_vmcb->dr6;
> +
> + /* RFLAGS */
> + host_vmcb->rflags = ns_vmcb->rflags;
> +
> + /* RIP */
> + host_vmcb->rip = ns_vmcb->rip;
> +
> + /* RSP */
> + host_vmcb->rsp = ns_vmcb->rsp;
> +
> + /* RAX */
> + host_vmcb->rax = ns_vmcb->rax;
> +
> + /* Keep the host values of the fs, gs, ldtr, tr, kerngsbase,
> + * star, lstar, cstar, sfmask, sysenter_cs, sysenter_esp,
> + * sysenter_eip. These are handled via VMSAVE/VMLOAD emulation.
> + */
> +
> + /* Page tables */
> + host_vmcb->pdpe0 = ns_vmcb->pdpe0;
> + host_vmcb->pdpe1 = ns_vmcb->pdpe1;
> + host_vmcb->pdpe2 = ns_vmcb->pdpe2;
> + host_vmcb->pdpe3 = ns_vmcb->pdpe3;
> +
> + /* PAT */
> + host_vmcb->g_pat = ns_vmcb->g_pat;
> +
> + /* Debug Control MSR */
> + host_vmcb->debugctlmsr = ns_vmcb->debugctlmsr;
> +
> + /* LBR MSRs */
> + host_vmcb->lastbranchfromip = ns_vmcb->lastbranchfromip;
> + host_vmcb->lastbranchtoip = ns_vmcb->lastbranchtoip;
> + host_vmcb->lastintfromip = ns_vmcb->lastintfromip;
> + host_vmcb->lastinttoip = ns_vmcb->lastinttoip;
> +
> + rc = svm_vmcb_isvalid(__func__, ns_vmcb, 1);
> + if (rc) {
> + gdprintk(XENLOG_ERR, "nested vmcb invalid\n");
> + return rc;
> + }
> +
> + rc = svm_vmcb_isvalid(__func__, host_vmcb, 1);
> + if (rc) {
> + gdprintk(XENLOG_ERR, "host vmcb invalid\n");
> + return rc;
> + }
> +
> + /* Switch guest registers to nested guest */
> + regs->eax = ns_vmcb->rax;
> + regs->eip = ns_vmcb->rip;
> + regs->esp = ns_vmcb->rsp;
> + regs->eflags = ns_vmcb->rflags;
> +
> + return 0;
> +}
> +
> +int
> +nsvm_vmcb_guest_intercepts_exitcode(struct vcpu *v,
> + struct cpu_user_regs *regs, uint64_t exitcode)
> +{
> + uint64_t exit_bits;
> + struct nestedvcpu *nv = &vcpu_nestedhvm(v);
> + struct nestedsvm *svm = &vcpu_nestedsvm(v);
> + struct vmcb_struct *ns_vmcb = nv->nv_vmcx;
> + enum nestedhvm_vmexits vmexits;
> +
> + switch (exitcode) {
> + case VMEXIT_CR0_READ ... VMEXIT_CR15_READ:
> + case VMEXIT_CR0_WRITE ... VMEXIT_CR15_WRITE:
> + exit_bits = 1ULL << (exitcode - VMEXIT_CR0_READ);
> + if (svm->ns_cr_intercepts & exit_bits)
> + break;
> + return 0;
> +
> + case VMEXIT_DR0_READ ... VMEXIT_DR7_READ:
> + case VMEXIT_DR0_WRITE ... VMEXIT_DR7_WRITE:
> + exit_bits = 1ULL << (exitcode - VMEXIT_DR0_READ);
> + if (svm->ns_dr_intercepts & exit_bits)
> + break;
> + return 0;
> +
> + case VMEXIT_EXCEPTION_DE ... VMEXIT_EXCEPTION_XF:
> + exit_bits = 1ULL << (exitcode - VMEXIT_EXCEPTION_DE);
> + if (svm->ns_exception_intercepts & exit_bits)
> + break;
> + return 0;
> +
> + case VMEXIT_INTR ... VMEXIT_SHUTDOWN:
> + exit_bits = 1ULL << (exitcode - VMEXIT_INTR);
> + if (svm->ns_general1_intercepts & exit_bits)
> + break;
> + return 0;
> +
> + case VMEXIT_VMRUN ... VMEXIT_MWAIT_CONDITIONAL:
> + exit_bits = 1ULL << (exitcode - VMEXIT_VMRUN);
> + if (svm->ns_general2_intercepts & exit_bits)
> + break;
> + return 0;
> +
> + case VMEXIT_NPF:
> + case VMEXIT_INVALID:
> + /* Always intercepted */
> + break;
> +
> + default:
> + gdprintk(XENLOG_ERR, "Illegal exitcode 0x%"PRIx64"\n", exitcode);
> + BUG();
> + break;
> + }
> +
> + /* Special cases: Do more detailed checks */
> + switch (exitcode) {
> + case VMEXIT_MSR:
> + ASSERT(regs != NULL);
> + nestedsvm_vmcb_map(v, nv->nv_vmcxaddr);
> + ASSERT(nv->nv_vmcx != NULL);
> + ns_vmcb = nv->nv_vmcx;
> + vmexits = nsvm_vmcb_guest_intercepts_msr(svm->ns_cached_msrpm,
> + regs->ecx, ns_vmcb->exitinfo1 != 0);
> + if (vmexits == NESTEDHVM_VMEXIT_HOST)
> + return 0;
> + break;
> +
> + case VMEXIT_IOIO:
> + /* always intercepted */
> + break;
What if the guest doesn't want to intercept it? Won't that make it
crash or misbehave?
Tim.
--
Tim Deegan <Tim.Deegan@xxxxxxxxxx>
Principal Software Engineer, Xen Platform Team
Citrix Systems UK Ltd. (Company #02937203, SL9 0BG)
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