On Fri, Jun 29, 2018 at 11:48:16AM +0200, Greg Kurz wrote: > Now that we're checking our MMU configuration is supported by KVM, > rather than adjusting it to KVM, it doesn't really make sense to > have a fallback for kvm_get_smmu_info(). If KVM is too old or buggy > to provide the details, we should rather treat this as an error. > > This patch thus adds error reporting to kvm_get_smmu_info() and get > rid of the fallback code. QEMU will now terminate if KVM fails to > provide MMU details. This may break some very old setups, but the > simplification is worth the sacrifice. > > Signed-off-by: Greg Kurz <gr...@kaod.org>
Ok, so immediately failing with an old kernel wasn't actually what I
had in mind. Instead I was suggesting just skipping the checks and
hoping for the best. Still, either way the relevant kernels are
really ancient now, so I'll apply anyway.
> ---
> target/ppc/kvm.c | 117
> +++++++++---------------------------------------------
> 1 file changed, 20 insertions(+), 97 deletions(-)
>
> diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
> index 4df4ff6cbff2..b6000f12b98f 100644
> --- a/target/ppc/kvm.c
> +++ b/target/ppc/kvm.c
> @@ -248,107 +248,25 @@ static int kvm_booke206_tlb_init(PowerPCCPU *cpu)
>
>
> #if defined(TARGET_PPC64)
> -static void kvm_get_fallback_smmu_info(PowerPCCPU *cpu,
> - struct kvm_ppc_smmu_info *info)
> +static void kvm_get_smmu_info(PowerPCCPU *cpu, struct kvm_ppc_smmu_info
> *info,
> + Error **errp)
> {
> - CPUPPCState *env = &cpu->env;
> CPUState *cs = CPU(cpu);
> + int ret;
>
> - memset(info, 0, sizeof(*info));
> -
> - /* We don't have the new KVM_PPC_GET_SMMU_INFO ioctl, so
> - * need to "guess" what the supported page sizes are.
> - *
> - * For that to work we make a few assumptions:
> - *
> - * - Check whether we are running "PR" KVM which only supports 4K
> - * and 16M pages, but supports them regardless of the backing
> - * store characteritics. We also don't support 1T segments.
> - *
> - * This is safe as if HV KVM ever supports that capability or PR
> - * KVM grows supports for more page/segment sizes, those versions
> - * will have implemented KVM_CAP_PPC_GET_SMMU_INFO and thus we
> - * will not hit this fallback
> - *
> - * - Else we are running HV KVM. This means we only support page
> - * sizes that fit in the backing store. Additionally we only
> - * advertize 64K pages if the processor is ARCH 2.06 and we assume
> - * P7 encodings for the SLB and hash table. Here too, we assume
> - * support for any newer processor will mean a kernel that
> - * implements KVM_CAP_PPC_GET_SMMU_INFO and thus doesn't hit
> - * this fallback.
> - */
> - if (kvmppc_is_pr(cs->kvm_state)) {
> - /* No flags */
> - info->flags = 0;
> - info->slb_size = 64;
> -
> - /* Standard 4k base page size segment */
> - info->sps[0].page_shift = 12;
> - info->sps[0].slb_enc = 0;
> - info->sps[0].enc[0].page_shift = 12;
> - info->sps[0].enc[0].pte_enc = 0;
> -
> - /* Standard 16M large page size segment */
> - info->sps[1].page_shift = 24;
> - info->sps[1].slb_enc = SLB_VSID_L;
> - info->sps[1].enc[0].page_shift = 24;
> - info->sps[1].enc[0].pte_enc = 0;
> - } else {
> - int i = 0;
> -
> - /* HV KVM has backing store size restrictions */
> - info->flags = KVM_PPC_PAGE_SIZES_REAL;
> -
> - if (ppc_hash64_has(cpu, PPC_HASH64_1TSEG)) {
> - info->flags |= KVM_PPC_1T_SEGMENTS;
> - }
> -
> - if (env->mmu_model == POWERPC_MMU_2_06 ||
> - env->mmu_model == POWERPC_MMU_2_07) {
> - info->slb_size = 32;
> - } else {
> - info->slb_size = 64;
> - }
> -
> - /* Standard 4k base page size segment */
> - info->sps[i].page_shift = 12;
> - info->sps[i].slb_enc = 0;
> - info->sps[i].enc[0].page_shift = 12;
> - info->sps[i].enc[0].pte_enc = 0;
> - i++;
> -
> - /* 64K on MMU 2.06 and later */
> - if (env->mmu_model == POWERPC_MMU_2_06 ||
> - env->mmu_model == POWERPC_MMU_2_07) {
> - info->sps[i].page_shift = 16;
> - info->sps[i].slb_enc = 0x110;
> - info->sps[i].enc[0].page_shift = 16;
> - info->sps[i].enc[0].pte_enc = 1;
> - i++;
> - }
> -
> - /* Standard 16M large page size segment */
> - info->sps[i].page_shift = 24;
> - info->sps[i].slb_enc = SLB_VSID_L;
> - info->sps[i].enc[0].page_shift = 24;
> - info->sps[i].enc[0].pte_enc = 0;
> + if (!kvm_check_extension(cs->kvm_state, KVM_CAP_PPC_GET_SMMU_INFO)) {
> + error_setg(errp, "KVM doesn't expose the MMU features it supports");
> + error_append_hint(errp, "Consider switching to a newer KVM\n");
> + return;
> }
> -}
> -
> -static void kvm_get_smmu_info(PowerPCCPU *cpu, struct kvm_ppc_smmu_info
> *info)
> -{
> - CPUState *cs = CPU(cpu);
> - int ret;
>
> - if (kvm_check_extension(cs->kvm_state, KVM_CAP_PPC_GET_SMMU_INFO)) {
> - ret = kvm_vm_ioctl(cs->kvm_state, KVM_PPC_GET_SMMU_INFO, info);
> - if (ret == 0) {
> - return;
> - }
> + ret = kvm_vm_ioctl(cs->kvm_state, KVM_PPC_GET_SMMU_INFO, info);
> + if (ret == 0) {
> + return;
> }
>
> - kvm_get_fallback_smmu_info(cpu, info);
> + error_setg_errno(errp, -ret,
> + "KVM failed to provide the MMU features it supports");
> }
>
> struct ppc_radix_page_info *kvm_get_radix_page_info(void)
> @@ -415,7 +333,7 @@ bool kvmppc_hpt_needs_host_contiguous_pages(void)
> return false;
> }
>
> - kvm_get_smmu_info(cpu, &smmu_info);
> + kvm_get_smmu_info(cpu, &smmu_info, &error_fatal);
> return !!(smmu_info.flags & KVM_PPC_PAGE_SIZES_REAL);
> }
>
> @@ -423,13 +341,18 @@ void kvm_check_mmu(PowerPCCPU *cpu, Error **errp)
> {
> struct kvm_ppc_smmu_info smmu_info;
> int iq, ik, jq, jk;
> + Error *local_err = NULL;
>
> /* For now, we only have anything to check on hash64 MMUs */
> if (!cpu->hash64_opts || !kvm_enabled()) {
> return;
> }
>
> - kvm_get_smmu_info(cpu, &smmu_info);
> + kvm_get_smmu_info(cpu, &smmu_info, &local_err);
> + if (local_err) {
> + error_propagate(errp, local_err);
> + return;
> + }
>
> if (ppc_hash64_has(cpu, PPC_HASH64_1TSEG)
> && !(smmu_info.flags & KVM_PPC_1T_SEGMENTS)) {
> @@ -2168,7 +2091,7 @@ uint64_t kvmppc_rma_size(uint64_t current_size,
> unsigned int hash_shift)
>
> /* Find the largest hardware supported page size that's less than
> * or equal to the (logical) backing page size of guest RAM */
> - kvm_get_smmu_info(POWERPC_CPU(first_cpu), &info);
> + kvm_get_smmu_info(POWERPC_CPU(first_cpu), &info, &error_fatal);
> rampagesize = qemu_getrampagesize();
> best_page_shift = 0;
>
>
--
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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