This patch is based on Bharata's v11 KVM patches for secure guests: https://lists.ozlabs.org/pipermail/linuxppc-dev/2019-November/200918.html --- >From c0826bac72a658312f3d87e0bb18ecaf08ac2b2e Mon Sep 17 00:00:00 2001 From: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxxxxxxx> Date: Fri, 27 Sep 2019 14:30:36 -0500 Subject: [PATCH v2 1/1] KVM: PPC: Implement H_SVM_INIT_ABORT hcall Implement the H_SVM_INIT_ABORT hcall which the Ultravisor can use to abort an SVM after it has issued the H_SVM_INIT_START and before the H_SVM_INIT_DONE hcalls. This hcall could be used when Ultravisor encounters security violations or other errors when starting an SVM. Note that this hcall is different from UV_SVM_TERMINATE ucall which is used by HV to terminate/cleanup an VM that has becore secure. The H_SVM_INIT_ABORT should basically undo operations that were done since the H_SVM_INIT_START hcall - i.e page-out all the VM pages back to normal memory, unregister memslots etc. (If we do not bring the pages back to normal memory, the text/data of the VM would be stuck in secure memory and since the SVM did not go secure, its MSR_S bit will be clear and the VM wont be able to access its pages even to do a clean exit). Based on patches and discussion with Paul Mackerras, Ram Pai and Bharata Rao. Signed-off-by: Ram Pai <linuxram@xxxxxxxxxxxxx> Signed-off-by: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxx> Signed-off-by: Bharata B Rao <bharata@xxxxxxxxxxxxx> --- Changelog[v2]: [Paul Mackerras] avoid returning to UV "one last time" after the state is cleaned up. So, we now have H_SVM_INIT_ABORT: - take the VM's NIP/MSR register states as parameters - inherit the state of other registers as at UV_ESM call. After cleaning up the partial state, HV uses these to return directly to the VM with a failed UV_ESM call. --- Documentation/powerpc/ultravisor.rst | 56 +++++++++++++++++++++ arch/powerpc/include/asm/hvcall.h | 1 + arch/powerpc/include/asm/kvm_book3s_uvmem.h | 10 +++- arch/powerpc/include/asm/kvm_host.h | 1 + arch/powerpc/kvm/book3s_64_mmu_radix.c | 2 +- arch/powerpc/kvm/book3s_hv.c | 5 +- arch/powerpc/kvm/book3s_hv_uvmem.c | 48 +++++++++++++++++- 7 files changed, 117 insertions(+), 6 deletions(-) diff --git a/Documentation/powerpc/ultravisor.rst b/Documentation/powerpc/ultravisor.rst index 730854f73830..ef49c9192775 100644 --- a/Documentation/powerpc/ultravisor.rst +++ b/Documentation/powerpc/ultravisor.rst @@ -948,6 +948,62 @@ Use cases up its internal state for this virtual machine. +H_SVM_INIT_ABORT +---------------- + + Abort the process of securing an SVM. + +Syntax +~~~~~~ + +.. code-block:: c + + uint64_t hypercall(const uint64_t H_SVM_INIT_ABORT, + uint64_t guest_pc, /* guest NIP to return to */ + uint64_t guest_msr, /* guest MSR value */ + +Return values +~~~~~~~~~~~~~ + + One of the following values: + + * H_PARAMETER on successfully cleaning up the state, Hypervisor will + return this value to the **guest**, to indicate that the underlying + UV_ESM ultra call failed. + + * H_UNSUPPORTED if called from the wrong context (e.g. from an SVM + or before an H_SVM_INIT_START hypercall). This will return to the + Ultravisor which incorrectly issued the hcall. + + +Description +~~~~~~~~~~~ + + Abort the process of securing a virtual machine. This call must + be made after a prior call to ``H_SVM_INIT_START`` hypercall and + before a call to ``H_SVM_INIT_DONE``. + + This hcall will cleanup any partial state that was established for + the VM since the prior ``H_SVM_INIT_START hcall`` including paging + out pages that were paged-into secure memory, unregistering memory + slots etc. + + After the partial state is cleaned up, control returns to the address + specified in ``guest_pc`` with the MSR values set to ``guest_msr``. + These parameters are expected to match the state of NIP and MSR + registers of the VM at the time it issued the ``UV_ESM`` ultra call + to transition to a secure VM. + +Use cases +~~~~~~~~~ + + If after a successful call to ``H_SVM_INIT_START``, the Ultravisor + encounters an error while securing a virtual machine, either due + to lack of resources or because the VM's security information could + not be validated, Ultravisor informs the Hypervisor about it. + Hypervisor should use this call to clean up any internal state for + this virtual machine and return to the VM. + H_SVM_PAGE_IN ------------- diff --git a/arch/powerpc/include/asm/hvcall.h b/arch/powerpc/include/asm/hvcall.h index 13bd870609c3..e90c073e437e 100644 --- a/arch/powerpc/include/asm/hvcall.h +++ b/arch/powerpc/include/asm/hvcall.h @@ -350,6 +350,7 @@ #define H_SVM_PAGE_OUT 0xEF04 #define H_SVM_INIT_START 0xEF08 #define H_SVM_INIT_DONE 0xEF0C +#define H_SVM_INIT_ABORT 0xEF14 /* Values for 2nd argument to H_SET_MODE */ #define H_SET_MODE_RESOURCE_SET_CIABR 1 diff --git a/arch/powerpc/include/asm/kvm_book3s_uvmem.h b/arch/powerpc/include/asm/kvm_book3s_uvmem.h index 50204e228f16..2453bed88b97 100644 --- a/arch/powerpc/include/asm/kvm_book3s_uvmem.h +++ b/arch/powerpc/include/asm/kvm_book3s_uvmem.h @@ -19,8 +19,9 @@ unsigned long kvmppc_h_svm_page_out(struct kvm *kvm, unsigned long kvmppc_h_svm_init_start(struct kvm *kvm); unsigned long kvmppc_h_svm_init_done(struct kvm *kvm); int kvmppc_send_page_to_uv(struct kvm *kvm, unsigned long gfn); +unsigned long kvmppc_h_svm_init_abort(struct kvm_vcpu *vcpu); void kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free, - struct kvm *kvm); + struct kvm *kvm, bool skip_page_out); #else static inline int kvmppc_uvmem_init(void) { @@ -62,6 +63,11 @@ static inline unsigned long kvmppc_h_svm_init_done(struct kvm *kvm) return H_UNSUPPORTED; } +static inline unsigned long kvmppc_h_svm_init_abort(struct kvm_vcpu *vcpu) +{ + return H_UNSUPPORTED; +} + static inline int kvmppc_send_page_to_uv(struct kvm *kvm, unsigned long gfn) { return -EFAULT; @@ -69,6 +75,6 @@ static inline int kvmppc_send_page_to_uv(struct kvm *kvm, unsigned long gfn) static inline void kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free, - struct kvm *kvm) { } + struct kvm *kvm, bool skip_page_out) { } #endif /* CONFIG_PPC_UV */ #endif /* __ASM_KVM_BOOK3S_UVMEM_H__ */ diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h index 577ca95fac7c..8310c0407383 100644 --- a/arch/powerpc/include/asm/kvm_host.h +++ b/arch/powerpc/include/asm/kvm_host.h @@ -278,6 +278,7 @@ struct kvm_resize_hpt; /* Flag values for kvm_arch.secure_guest */ #define KVMPPC_SECURE_INIT_START 0x1 /* H_SVM_INIT_START has been called */ #define KVMPPC_SECURE_INIT_DONE 0x2 /* H_SVM_INIT_DONE completed */ +#define KVMPPC_SECURE_INIT_ABORT 0x4 /* H_SVM_INIT_ABORT issued */ struct kvm_arch { unsigned int lpid; diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c index da857c8ba6e4..744dba98e5d1 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_radix.c +++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c @@ -1102,7 +1102,7 @@ void kvmppc_radix_flush_memslot(struct kvm *kvm, unsigned int shift; if (kvm->arch.secure_guest & KVMPPC_SECURE_INIT_START) - kvmppc_uvmem_drop_pages(memslot, kvm); + kvmppc_uvmem_drop_pages(memslot, kvm, true); if (kvm->arch.secure_guest & KVMPPC_SECURE_INIT_DONE) return; diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 597f4bfecf0e..b883d947d038 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -1099,6 +1099,9 @@ int kvmppc_pseries_do_hcall(struct kvm_vcpu *vcpu) case H_SVM_INIT_DONE: ret = kvmppc_h_svm_init_done(vcpu->kvm); break; + case H_SVM_INIT_ABORT: + ret = kvmppc_h_svm_init_abort(vcpu); + break; default: return RESUME_HOST; @@ -5493,7 +5496,7 @@ static int kvmhv_svm_off(struct kvm *kvm) continue; kvm_for_each_memslot(memslot, slots) { - kvmppc_uvmem_drop_pages(memslot, kvm); + kvmppc_uvmem_drop_pages(memslot, kvm, true); uv_unregister_mem_slot(kvm->arch.lpid, memslot->id); } } diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c index f24ac3cfb34c..881017dc8ff1 100644 --- a/arch/powerpc/kvm/book3s_hv_uvmem.c +++ b/arch/powerpc/kvm/book3s_hv_uvmem.c @@ -259,7 +259,7 @@ unsigned long kvmppc_h_svm_init_done(struct kvm *kvm) * QEMU page table with normal PTEs from newly allocated pages. */ void kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free, - struct kvm *kvm) + struct kvm *kvm, bool skip_page_out) { int i; struct kvmppc_uvmem_page_pvt *pvt; @@ -277,7 +277,8 @@ void kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free, uvmem_page = pfn_to_page(uvmem_pfn); pvt = uvmem_page->zone_device_data; - pvt->skip_page_out = true; + pvt->skip_page_out = skip_page_out; + mutex_unlock(&kvm->arch.uvmem_lock); pfn = gfn_to_pfn(kvm, gfn); @@ -287,6 +288,49 @@ void kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free, } } +unsigned long kvmppc_h_svm_init_abort(struct kvm_vcpu *vcpu) +{ + int i; + ulong pc, msr; + struct kvm *kvm = vcpu->kvm; + + pc = kvmppc_get_gpr(vcpu, 4); + msr = kvmppc_get_gpr(vcpu, 5); + + if (!(kvm->arch.secure_guest & KVMPPC_SECURE_INIT_START)) + return H_UNSUPPORTED; + + /* + * we expect a guest address and guest MSR, so MSR_HV should + * not be set. Warn and proceed to terminate the VM. + */ + if (msr & MSR_HV) { + pr_warning("MSR_HV set on H_SVM_INIT_ABORT call!\n"); + msr &= ~MSR_HV; + } + + for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { + struct kvm_memory_slot *memslot; + struct kvm_memslots *slots = __kvm_memslots(kvm, i); + + if (!slots) + continue; + + kvm_for_each_memslot(memslot, slots) { + kvmppc_uvmem_drop_pages(memslot, kvm, false); + uv_unregister_mem_slot(kvm->arch.lpid, memslot->id); + } + } + + kvm->arch.secure_guest = 0; + + /* Return to the point where VM issued UV_ESM ucall */ + kvmppc_set_pc(vcpu, pc); + kvmppc_set_msr(vcpu, msr); + + return H_PARAMETER; +} + /* * Get a free device PFN from the pool * -- 2.17.2
