On Fri, Sep 21, 2018 at 08:01:54PM +1000, Paul Mackerras wrote:
> From: Suraj Jitindar Singh <sjitindarsingh@xxxxxxxxx>
>
> A HEAI (hypervisor emulation assistance interrupt) occurs when a
> hypervisor resource or instruction is used in a privileged but
> non-hypervisor state and the LPCR_EVIRT bit is set in LPCR. When
> this occurs bit 45 is set in HSRR1. Detect the occurrence of this,
> and if userspace has enabled the nested virtualization capability
> on the VM, then call the code to handle it accordingly.
>
> With LPCR[EVIRT] set, we also get HEAI (without bit 45 set) for
> mfspr or mtspr to unimplemented SPR numbers. For these accesses,
> we emulate the EVIRT=0 behaviour, which is to make the access
> a no-op for privileged software unless it is accessing SPR 0,
> 4, 5 or 6. Problem-state accesses and accesses to SPR 0, 4, 5
> or 6 generate an illegal-instruction type program interrupt.
>
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@xxxxxxxxx>
> Signed-off-by: Paul Mackerras <paulus@xxxxxxxxxx>
Reviewed-by: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
Question, though: with the new mostly-paravirt approach to nested
virt, what HV instructions do you still need to emulate?
> ---
> arch/powerpc/include/asm/kvm_book3s.h | 2 +
> arch/powerpc/kvm/book3s_hv.c | 87 ++++++++++++++++++++++-------------
> arch/powerpc/kvm/book3s_hv_nested.c | 55 ++++++++++++++++++++++
> 3 files changed, 112 insertions(+), 32 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h
> index 125bc5b..a22a501 100644
> --- a/arch/powerpc/include/asm/kvm_book3s.h
> +++ b/arch/powerpc/include/asm/kvm_book3s.h
> @@ -287,6 +287,8 @@ void kvmhv_save_hv_regs(struct kvm_vcpu *vcpu, struct hv_guest_state *hr);
> void kvmhv_restore_hv_return_state(struct kvm_vcpu *vcpu,
> struct hv_guest_state *hr);
> long int kvmhv_nested_page_fault(struct kvm_vcpu *vcpu);
> +int kvmhv_emulate_priv(struct kvm_run *run, struct kvm_vcpu *vcpu,
> + unsigned int instr);
>
> void kvmppc_giveup_fac(struct kvm_vcpu *vcpu, ulong fac);
>
> diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
> index 61de6ac..3b78d97 100644
> --- a/arch/powerpc/kvm/book3s_hv.c
> +++ b/arch/powerpc/kvm/book3s_hv.c
> @@ -1024,30 +1024,6 @@ static int kvmppc_hcall_impl_hv(unsigned long cmd)
> return kvmppc_hcall_impl_hv_realmode(cmd);
> }
>
> -static int kvmppc_emulate_debug_inst(struct kvm_run *run,
> - struct kvm_vcpu *vcpu)
> -{
> - u32 last_inst;
> -
> - if (kvmppc_get_last_inst(vcpu, INST_GENERIC, &last_inst) !=
> - EMULATE_DONE) {
> - /*
> - * Fetch failed, so return to guest and
> - * try executing it again.
> - */
> - return RESUME_GUEST;
> - }
> -
> - if (last_inst == KVMPPC_INST_SW_BREAKPOINT) {
> - run->exit_reason = KVM_EXIT_DEBUG;
> - run->debug.arch.address = kvmppc_get_pc(vcpu);
> - return RESUME_HOST;
> - } else {
> - kvmppc_core_queue_program(vcpu, SRR1_PROGILL);
> - return RESUME_GUEST;
> - }
> -}
> -
> static void do_nothing(void *x)
> {
> }
> @@ -1141,6 +1117,23 @@ static int kvmppc_emulate_doorbell_instr(struct kvm_vcpu *vcpu)
> return RESUME_GUEST;
> }
>
> +static int kvmhv_emulate_unknown_spr(struct kvm_vcpu *vcpu, u32 instr)
> +{
> + u32 spr = get_sprn(instr);
> +
> + /*
> + * In privileged state, access to unimplemented SPRs is a no-op
> + * except for SPR 0, 4, 5 and 6. All other accesses get turned
> + * into illegal-instruction program interrupts.
> + */
> + if ((vcpu->arch.shregs.msr & MSR_PR) ||
> + spr == 0 || (4 <= spr && spr <= 6))
> + return EMULATE_FAIL;
> +
> + kvmppc_set_pc(vcpu, kvmppc_get_pc(vcpu) + 4);
> + return RESUME_GUEST;
> +}
> +
> static int kvmppc_handle_exit_hv(struct kvm_run *run, struct kvm_vcpu *vcpu,
> struct task_struct *tsk)
> {
> @@ -1257,19 +1250,49 @@ static int kvmppc_handle_exit_hv(struct kvm_run *run, struct kvm_vcpu *vcpu,
> * to the guest. If guest debug is enabled, we need to check
> * whether the instruction is a software breakpoint instruction.
> * Accordingly return to Guest or Host.
> + * With LPCR[EVIRT] set, we also get these for accesses to
> + * unknown SPRs and for guests executing hypervisor privileged
> + * instructions.
> */
> case BOOK3S_INTERRUPT_H_EMUL_ASSIST:
> - if (vcpu->arch.emul_inst != KVM_INST_FETCH_FAILED)
> - vcpu->arch.last_inst = kvmppc_need_byteswap(vcpu) ?
> - swab32(vcpu->arch.emul_inst) :
> - vcpu->arch.emul_inst;
> - if (vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP) {
> - r = kvmppc_emulate_debug_inst(run, vcpu);
> + {
> + u32 instr = vcpu->arch.emul_inst;
> + unsigned long srr1_bit = SRR1_PROGILL;
> +
> + vcpu->arch.last_inst = kvmppc_need_byteswap(vcpu) ?
> + swab32(instr) : instr;
> +
> + r = EMULATE_FAIL;
> + if (vcpu->arch.shregs.msr & SRR1_PROGPRIV) {
> + /*
> + * Tried to execute hypervisor privileged instruction
> + * or mtspr/mfspr on a hypervisor privileged SPR while
> + * MSR(HV | PR) == 0b00 -> Privileged but !HV state
> + */
> + srr1_bit = SRR1_PROGPRIV;
> + if (vcpu->kvm->arch.nested_enable)
> + r = kvmhv_emulate_priv(run, vcpu, instr);
> } else {
> - kvmppc_core_queue_program(vcpu, SRR1_PROGILL);
> + /* Illegal instruction or unknown SPR access */
> + if (instr == KVMPPC_INST_SW_BREAKPOINT &&
> + (vcpu->guest_debug & KVM_GUESTDBG_USE_SW_BP)) {
> + run->exit_reason = KVM_EXIT_DEBUG;
> + run->debug.arch.address = kvmppc_get_pc(vcpu);
> + r = RESUME_HOST;
> + break;
> + }
> + if ((instr & 0xfc0006fe) == PPC_INST_MFSPR)
> + /* mfspr or mtspr to unknown SPR, may be noop */
> + r = kvmhv_emulate_unknown_spr(vcpu, instr);
> + }
> + if (r == EMULATE_FAIL) {
> + pr_debug("KVM: Couldn't emulate instruction 0x%.8x\n",
> + instr);
> + kvmppc_core_queue_program(vcpu, srr1_bit);
> r = RESUME_GUEST;
> }
> break;
> + }
> /*
> * This occurs if the guest (kernel or userspace), does something that
> * is prohibited by HFSCR.
> @@ -4597,7 +4620,7 @@ static int kvmppc_core_init_vm_hv(struct kvm *kvm)
> */
> if (cpu_has_feature(CPU_FTR_ARCH_300)) {
> lpcr &= ~LPCR_VPM0;
> - lpcr |= LPCR_HVICE | LPCR_HEIC;
> + lpcr |= LPCR_HVICE | LPCR_HEIC | LPCR_EVIRT;
>
> /*
> * If xive is enabled, we route 0x500 interrupts directly
> diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3s_hv_nested.c
> index a7f3da9..93ecf3b 100644
> --- a/arch/powerpc/kvm/book3s_hv_nested.c
> +++ b/arch/powerpc/kvm/book3s_hv_nested.c
> @@ -15,6 +15,7 @@
> #include <asm/mmu.h>
> #include <asm/pgtable.h>
> #include <asm/pgalloc.h>
> +#include <asm/disassemble.h>
>
> static struct patb_entry *pseries_partition_tb;
>
> @@ -514,3 +515,57 @@ long kvmhv_nested_page_fault(struct kvm_vcpu *vcpu)
> {
> return RESUME_HOST;
> }
> +
> +static int kvmhv_emulate_priv_mtspr(struct kvm_run *run, struct kvm_vcpu *vcpu,
> + unsigned int instr)
> +{
> + return EMULATE_FAIL;
> +}
> +
> +static int kvmhv_emulate_priv_mfspr(struct kvm_run *run, struct kvm_vcpu *vcpu,
> + unsigned int instr)
> +{
> + return EMULATE_FAIL;
> +}
> +
> +static int kvmhv_emulate_priv_op_31(struct kvm_run *run, struct kvm_vcpu *vcpu,
> + unsigned int instr)
> +{
> + return EMULATE_FAIL;
> +}
> +
> +static int kvmhv_emulate_priv_op(struct kvm_run *run, struct kvm_vcpu *vcpu,
> + unsigned int instr)
> +{
> + return EMULATE_FAIL;
> +}
> +
> +int kvmhv_emulate_priv(struct kvm_run *run, struct kvm_vcpu *vcpu,
> + unsigned int instr)
> +{
> + int rc = EMULATE_FAIL;
> +
> + switch (get_op(instr)) {
> + case 31:
> + switch (get_xop(instr)) {
> + case OP_31_XOP_MTSPR:
> + rc = kvmhv_emulate_priv_mtspr(run, vcpu, instr);
> + break;
> + case OP_31_XOP_MFSPR:
> + rc = kvmhv_emulate_priv_mfspr(run, vcpu, instr);
> + break;
> + default:
> + rc = kvmhv_emulate_priv_op_31(run, vcpu, instr);
> + break;
> + }
> +
> + if (rc == EMULATE_DONE)
> + kvmppc_set_pc(vcpu, kvmppc_get_pc(vcpu) + 4);
> + break;
> + default:
> + rc = kvmhv_emulate_priv_op(run, vcpu, instr);
> + break;
> + }
> +
> + return rc;
> +}
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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