On 02/17/2012 11:13 AM, Alexander Graf wrote:
> From: Scott Wood <scottwood@xxxxxxxxxxxxx>
>
> Chips such as e500mc that implement category E.HV in Power ISA 2.06
> provide hardware virtualization features, including a new MSR mode for
> guest state. The guest OS can perform many operations without trapping
> into the hypervisor, including transitions to and from guest userspace.
>
> Since we can use SRR1[GS] to reliably tell whether an exception came from
> guest state, instead of messing around with IVPR, we use DO_KVM similarly
> to book3s.
>
> Current issues include:
> - Machine checks from guest state are not routed to the host handler.
> - The guest can cause a host oops by executing an emulated instruction
> in a page that lacks read permission. Existing e500/4xx support has
> the same problem.
>
> Includes work by Ashish Kalra <Ashish.Kalra@xxxxxxxxxxxxx>,
> Varun Sethi <Varun.Sethi@xxxxxxxxxxxxx>, and
> Liu Yu <yu.liu@xxxxxxxxxxxxx>.
>
> Signed-off-by: Scott Wood <scottwood@xxxxxxxxxxxxx>
> [agraf: remove pt_regs usage]
> Signed-off-by: Alexander Graf <agraf@xxxxxxx>
> ---
Thanks for picking this up!
> +static unsigned long get_guest_esr(struct kvm_vcpu *vcpu)
> +{
> +#ifdef CONFIG_KVM_BOOKE_HV
> + return mfspr(SPRN_ESR);
> +#else
> + return vcpu->arch.shared->esr;
> +#endif
> +}
s/SPRN_ESR/SPRN_GESR/
> int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
> unsigned int exit_nr)
> {
> - enum emulation_result er;
> int r = RESUME_HOST;
>
> /* update before a new last_exit_type is rewritten */
> kvmppc_update_timing_stats(vcpu);
>
> + switch (exit_nr) {
> + case BOOKE_INTERRUPT_EXTERNAL:
> + do_IRQ(current->thread.regs);
> + break;
What will current->thread.regs point to here? Something on the stack
from the last normal host exception entry?
We probably want to create a pt_regs on the stack and at least provide
PC, LR, and r1 for perfmon interrupts and such.
> @@ -384,30 +558,56 @@ int kvmppc_handle_exit(struct kvm_run *run, struct kvm_vcpu *vcpu,
>
> switch (exit_nr) {
> case BOOKE_INTERRUPT_MACHINE_CHECK:
> - printk("MACHINE CHECK: %lx\n", mfspr(SPRN_MCSR));
> - kvmppc_dump_vcpu(vcpu);
> - r = RESUME_HOST;
> + kvm_resched(vcpu);
> + r = RESUME_GUEST;
> break;
Leave this bit out (proper machine check handling will come later).
> case BOOKE_INTERRUPT_PROGRAM:
> - if (vcpu->arch.shared->msr & MSR_PR) {
> + if (vcpu->arch.shared->msr & (MSR_PR | MSR_GS)) {
> /* Program traps generated by user-level software must be handled
> * by the guest kernel. */
> kvmppc_core_queue_program(vcpu, vcpu->arch.fault_esr);
Should update the comment for why we're checking GS (i.e. we get a
different trap for emulation with GS-mode).
> +#define SET_VCPU(vcpu) \
> + PPC_STL vcpu, (THREAD + THREAD_KVM_VCPU)(r2)
Change spaces to tab before PPC_STL
> +#define LONGBYTES (BITS_PER_LONG / 8)
> +
> +#define VCPU_GPR(n) (VCPU_GPRS + (n * LONGBYTES))
> +#define VCPU_GUEST_SPRG(n) (VCPU_GUEST_SPRGS + (n * LONGBYTES))
> +
> +/* The host stack layout: */
> +#define HOST_R1 (0 * LONGBYTES) /* Implied by stwu. */
> +#define HOST_CALLEE_LR (1 * LONGBYTES)
> +#define HOST_RUN (2 * LONGBYTES) /* struct kvm_run */
> +/*
> + * r2 is special: it holds 'current', and it made nonvolatile in the
> + * kernel with the -ffixed-r2 gcc option.
> + */
> +#define HOST_R2 (3 * LONGBYTES)
> +#define HOST_NV_GPRS (4 * LONGBYTES)
> +#define HOST_NV_GPR(n) (HOST_NV_GPRS + ((n - 14) * LONGBYTES))
> +#define HOST_MIN_STACK_SIZE (HOST_NV_GPR(31) + LONGBYTES)
> +#define HOST_STACK_SIZE ((HOST_MIN_STACK_SIZE + 15) & ~15) /* Align. */
> +#define HOST_STACK_LR (HOST_STACK_SIZE + LONGBYTES) /* In caller stack frame. */
> +
> +#define NEED_EMU 0x00000001 /* emulation -- save nv regs */
> +#define NEED_DEAR 0x00000002 /* save faulting DEAR */
> +#define NEED_ESR 0x00000004 /* save faulting ESR */
> +
> +/*
> + * On entry:
> + * r4 = vcpu, r5 = srr0, r6 = srr1
> + * saved in vcpu: cr, ctr, r3-r13
> + */
> +.macro kvm_handler_common intno, srr0, flags
> + mfspr r10, SPRN_PID
> + lwz r8, VCPU_HOST_PID(r4)
> + PPC_LL r11, VCPU_SHARED(r4)
> + PPC_STL r14, VCPU_GPR(r14)(r4) /* We need a non-volatile GPR. */
> + li r14, \intno
> +
> + stw r10, VCPU_GUEST_PID(r4)
> + mtspr SPRN_PID, r8
> +
> + .if \flags & NEED_EMU
> + lwz r9, VCPU_KVM(r4)
> + .endif
> +
> +#ifdef CONFIG_KVM_EXIT_TIMING
> + /* save exit time */
> +1: mfspr r7, SPRN_TBRU
> + mfspr r8, SPRN_TBRL
> + mfspr r9, SPRN_TBRU
> + cmpw r9, r7
> + PPC_STL r8, VCPU_TIMING_EXIT_TBL(r4)
> + bne- 1b
> + PPC_STL r9, VCPU_TIMING_EXIT_TBU(r4)
> +#endif
As you pointed out to me last time, r9 is clobbered if exit timing is
enabled (but see below, the load of VCPU_KVM can be removed along with
the subsequent load of LVM_LPID(r9)).
> + oris r8, r6, MSR_CE@h
> +#ifndef CONFIG_64BIT
> + stw r6, (VCPU_SHARED_MSR + 4)(r11)
> +#else
> + std r6, (VCPU_SHARED_MSR)(r11)
> +#endif
> + ori r8, r8, MSR_ME | MSR_RI
> + PPC_STL r5, VCPU_PC(r4)
> +
> + /*
> + * Make sure CE/ME/RI are set (if appropriate for exception type)
> + * whether or not the guest had it set. Since mfmsr/mtmsr are
> + * somewhat expensive, skip in the common case where the guest
> + * had all these bits set (and thus they're still set if
> + * appropriate for the exception type).
> + */
> + cmpw r6, r8
> + .if \flags & NEED_EMU
> + lwz r9, KVM_LPID(r9)
> + .endif
Where do we use r9? This is probably left over from something old.
-Scott
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