Ram Pai [linuxram@xxxxxxxxxx] wrote:
>
> One small comment.. H_STATE is a better return code than H_UNSUPPORTED.
>
Here is the updated patch - we now return H_STATE if the abort call is
made after the VM has gone secure.
---
>From 73fe1fa5aff2829f2fae6a339169e56dc0bbae06 Mon Sep 17 00:00:00 2001
From: Sukadev Bhattiprolu <sukadev@xxxxxxxxxxxxx>
Date: Fri, 27 Sep 2019 14:30:36 -0500
Subject: [PATCH 2/2] 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, and terminate the SVM.
(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[v4]:
- [Bharata Rao] Add missing rcu locking
- [Paul Mackerras] simplify code that walks memslots
- Add a check to ensure that H_SVM_INIT_ABORT is called before
H_SVM_INIT_DONE hcall (i.e the SVM is not already secure).
- [Ram Pai] Return H_STATE if hcall is called after *INIT_DONE.
Changelog[v3]:
- Rather than pass the NIP/MSR as parameters, load them into
SRR0/SRR1 (like we do with other registers) and terminate
the VM after paging out pages
- Move the code to add a skip_page_out parameter into a
separate patch.
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 | 60 +++++++++++++++++++++
arch/powerpc/include/asm/hvcall.h | 1 +
arch/powerpc/include/asm/kvm_book3s_uvmem.h | 6 +++
arch/powerpc/include/asm/kvm_host.h | 1 +
arch/powerpc/kvm/book3s_hv.c | 3 ++
arch/powerpc/kvm/book3s_hv_uvmem.c | 28 ++++++++++
6 files changed, 99 insertions(+)
diff --git a/Documentation/powerpc/ultravisor.rst b/Documentation/powerpc/ultravisor.rst
index 730854f73830..363736d7fd36 100644
--- a/Documentation/powerpc/ultravisor.rst
+++ b/Documentation/powerpc/ultravisor.rst
@@ -948,6 +948,66 @@ 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)
+
+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 ultracall failed.
+
+ * H_STATE if called after a VM has gone secure (i.e
+ H_SVM_INIT_DONE hypercall was successful).
+
+ * H_UNSUPPORTED if called from a wrong context (e.g. from a
+ normal VM).
+
+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``.
+
+ On entry into this hypercall the non-volatile GPRs and FPRs are
+ expected to contain the values they had at the time the VM issued
+ the UV_ESM ultracall. Further ``SRR0`` is expected to contain the
+ address of the instruction after the ``UV_ESM`` ultracall and ``SRR1``
+ the MSR value with which to return to the VM.
+
+ This hypercall will cleanup any partial state that was established for
+ the VM since the prior ``H_SVM_INIT_START`` hypercall, including paging
+ out pages that were paged-into secure memory, and issue the
+ ``UV_SVM_TERMINATE`` ultracall to terminate the VM.
+
+ After the partial state is cleaned up, control returns to the VM
+ (**not Ultravisor**), at the address specified in ``SRR0`` with the
+ MSR values set to the value in ``SRR1``.
+
+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 3cf8425b9838..5a9834e0e2d1 100644
--- a/arch/powerpc/include/asm/kvm_book3s_uvmem.h
+++ b/arch/powerpc/include/asm/kvm_book3s_uvmem.h
@@ -19,6 +19,7 @@ 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 *kvm);
void kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free,
struct kvm *kvm, bool skip_page_out);
#else
@@ -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 *kvm)
+{
+ return H_UNSUPPORTED;
+}
+
static inline int kvmppc_send_page_to_uv(struct kvm *kvm, unsigned long gfn)
{
return -EFAULT;
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_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 66d5312be16b..1b22f2c7ad1b 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->kvm);
+ break;
default:
return RESUME_HOST;
diff --git a/arch/powerpc/kvm/book3s_hv_uvmem.c b/arch/powerpc/kvm/book3s_hv_uvmem.c
index 9a5bbad7d87e..522b57be0d45 100644
--- a/arch/powerpc/kvm/book3s_hv_uvmem.c
+++ b/arch/powerpc/kvm/book3s_hv_uvmem.c
@@ -287,6 +287,34 @@ void kvmppc_uvmem_drop_pages(const struct kvm_memory_slot *free,
}
}
+unsigned long kvmppc_h_svm_init_abort(struct kvm *kvm)
+{
+ int srcu_idx;
+ struct kvm_memory_slot *memslot;
+
+ /*
+ * Expect to be called only after INIT_START and before INIT_DONE.
+ * If INIT_DONE was completed, use normal VM termination sequence.
+ */
+ if (!(kvm->arch.secure_guest & KVMPPC_SECURE_INIT_START))
+ return H_UNSUPPORTED;
+
+ if (kvm->arch.secure_guest & KVMPPC_SECURE_INIT_DONE)
+ return H_STATE;
+
+ srcu_idx = srcu_read_lock(&kvm->srcu);
+
+ kvm_for_each_memslot(memslot, kvm_memslots(kvm))
+ kvmppc_uvmem_drop_pages(memslot, kvm, false);
+
+ srcu_read_unlock(&kvm->srcu, srcu_idx);
+
+ kvm->arch.secure_guest = 0;
+ uv_svm_terminate(kvm->arch.lpid);
+
+ return H_PARAMETER;
+}
+
/*
* Get a free device PFN from the pool
*
--
2.17.2
