From: Fuad Tabba <tabba@google.com>
To: kvmarm@lists.linux.dev
Cc: maz@kernel.org, will@kernel.org, qperret@google.com,
tabba@google.com, seanjc@google.com, alexandru.elisei@arm.com,
catalin.marinas@arm.com, philmd@linaro.org, james.morse@arm.com,
suzuki.poulose@arm.com, oliver.upton@linux.dev,
mark.rutland@arm.com, broonie@kernel.org, joey.gouly@arm.com,
rananta@google.com
Subject: [PATCH v1 44/44] KVM: arm64: Force injection of a data abort on NISV MMIO exit
Date: Wed, 27 Mar 2024 17:35:31 +0000 [thread overview]
Message-ID: <20240327173531.1379685-45-tabba@google.com> (raw)
In-Reply-To: <20240327173531.1379685-1-tabba@google.com>
From: Marc Zyngier <maz@kernel.org>
If a vcpu exits for a data abort with an invalid syndrome, the
expectations are that userspace has a chance to save the day if
it has requested to see such exits.
However, this is completely futile in the case of a protected VM,
as none of the state is available. In this particular case, inject
a data abort directly into the vcpu, consistent with what userspace
could do.
This also helps with pKVM, which discards all syndrome information when
forwarding data aborts that are not known to be MMIO.
Finally, hide the RETURN_NISV_IO_ABORT_TO_USER cap from userspace on
protected VMs, and document this tweak to the API.
Signed-off-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Fuad Tabba <tabba@google.com>
---
Documentation/virt/kvm/api.rst | 7 +++++++
arch/arm64/kvm/arm.c | 14 ++++++++++----
arch/arm64/kvm/mmio.c | 9 +++++++++
3 files changed, 26 insertions(+), 4 deletions(-)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 0b5a33ee71ee..b11b70ae137e 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -6894,6 +6894,13 @@ Note that KVM does not skip the faulting instruction as it does for
KVM_EXIT_MMIO, but userspace has to emulate any change to the processing state
if it decides to decode and emulate the instruction.
+This feature isn't available to protected VMs, as userspace does not
+have access to the state that is required to perform the emulation.
+Instead, a data abort exception is directly injected in the guest.
+Note that although KVM_CAP_ARM_NISV_TO_USER will be reported if
+queried outside of a protected VM context, the feature will not be
+exposed if queried on a protected VM file descriptor.
+
::
/* KVM_EXIT_X86_RDMSR / KVM_EXIT_X86_WRMSR */
diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
index 828bbd9e2d94..924010e8a8cc 100644
--- a/arch/arm64/kvm/arm.c
+++ b/arch/arm64/kvm/arm.c
@@ -80,9 +80,13 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
switch (cap->cap) {
case KVM_CAP_ARM_NISV_TO_USER:
- r = 0;
- set_bit(KVM_ARCH_FLAG_RETURN_NISV_IO_ABORT_TO_USER,
- &kvm->arch.flags);
+ if (kvm_vm_is_protected(kvm)) {
+ r = -EINVAL;
+ } else {
+ r = 0;
+ set_bit(KVM_ARCH_FLAG_RETURN_NISV_IO_ABORT_TO_USER,
+ &kvm->arch.flags);
+ }
break;
case KVM_CAP_ARM_MTE:
mutex_lock(&kvm->lock);
@@ -240,7 +244,6 @@ static int kvm_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_IMMEDIATE_EXIT:
case KVM_CAP_VCPU_EVENTS:
case KVM_CAP_ARM_IRQ_LINE_LAYOUT_2:
- case KVM_CAP_ARM_NISV_TO_USER:
case KVM_CAP_ARM_INJECT_EXT_DABT:
case KVM_CAP_SET_GUEST_DEBUG:
case KVM_CAP_VCPU_ATTRIBUTES:
@@ -250,6 +253,9 @@ static int kvm_check_extension(struct kvm *kvm, long ext)
case KVM_CAP_COUNTER_OFFSET:
r = 1;
break;
+ case KVM_CAP_ARM_NISV_TO_USER:
+ r = !kvm || !kvm_vm_is_protected(kvm);
+ break;
case KVM_CAP_SET_GUEST_DEBUG2:
return KVM_GUESTDBG_VALID_MASK;
case KVM_CAP_ARM_SET_DEVICE_ADDR:
diff --git a/arch/arm64/kvm/mmio.c b/arch/arm64/kvm/mmio.c
index 5e1ffb0d5363..87fd8faf2b62 100644
--- a/arch/arm64/kvm/mmio.c
+++ b/arch/arm64/kvm/mmio.c
@@ -133,11 +133,20 @@ int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa)
/*
* No valid syndrome? Ask userspace for help if it has
* volunteered to do so, and bail out otherwise.
+ *
+ * In the protected VM case, there isn't much userspace can do
+ * though, so directly deliver an exception to the guest.
*/
if (!kvm_vcpu_dabt_isvalid(vcpu)) {
trace_kvm_mmio_nisv(*vcpu_pc(vcpu), kvm_vcpu_get_esr(vcpu),
kvm_vcpu_get_hfar(vcpu), fault_ipa);
+ if (is_protected_kvm_enabled() &&
+ kvm_vm_is_protected(vcpu->kvm)) {
+ kvm_inject_dabt(vcpu, kvm_vcpu_get_hfar(vcpu));
+ return 1;
+ }
+
if (test_bit(KVM_ARCH_FLAG_RETURN_NISV_IO_ABORT_TO_USER,
&vcpu->kvm->arch.flags)) {
run->exit_reason = KVM_EXIT_ARM_NISV;
--
2.44.0.478.gd926399ef9-goog
prev parent reply other threads:[~2024-03-27 17:37 UTC|newest]
Thread overview: 64+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-27 17:34 [PATCH v1 00/44] KVM: arm64: Preamble for pKVM Fuad Tabba
2024-03-27 17:34 ` [PATCH v1 01/44] KVM: arm64: Change kvm_handle_mmio_return() return polarity Fuad Tabba
2024-03-27 17:34 ` [PATCH v1 02/44] KVM: arm64: Use enum instead of helper for checking FP-state Fuad Tabba
2024-03-28 16:19 ` Mark Brown
2024-04-08 7:39 ` Marc Zyngier
2024-04-08 13:39 ` Fuad Tabba
2024-03-27 17:34 ` [PATCH v1 03/44] KVM: arm64: Move setting the page as dirty out of the critical section Fuad Tabba
2024-04-08 7:41 ` Marc Zyngier
2024-04-08 15:41 ` Fuad Tabba
2024-04-08 15:53 ` Marc Zyngier
2024-04-08 15:57 ` Fuad Tabba
2024-03-27 17:34 ` [PATCH v1 04/44] KVM: arm64: Avoid BUG-ing from the host abort path Fuad Tabba
2024-04-08 7:44 ` Marc Zyngier
2024-04-08 13:48 ` Fuad Tabba
2024-03-27 17:34 ` [PATCH v1 05/44] KVM: arm64: Check for PTE validity when checking for executable/cacheable Fuad Tabba
2024-03-27 17:34 ` [PATCH v1 06/44] KVM: arm64: Avoid BBM when changing only s/w bits in Stage-2 PTE Fuad Tabba
2024-03-27 17:34 ` [PATCH v1 07/44] KVM: arm64: Support TLB invalidation in guest context Fuad Tabba
2024-04-15 11:36 ` Marc Zyngier
2024-04-15 15:02 ` Fuad Tabba
2024-04-15 15:59 ` Marc Zyngier
2024-03-27 17:34 ` [PATCH v1 08/44] KVM: arm64: Simplify vgic-v3 hypercalls Fuad Tabba
2024-03-27 17:34 ` [PATCH v1 09/44] KVM: arm64: Add is_pkvm_initialized() helper Fuad Tabba
2024-03-27 17:34 ` [PATCH v1 10/44] KVM: arm64: Introduce predicates to check for protected state Fuad Tabba
2024-03-27 17:34 ` [PATCH v1 11/44] KVM: arm64: Split up nvhe/fixed_config.h Fuad Tabba
2024-03-27 17:34 ` [PATCH v1 12/44] KVM: arm64: Move pstate reset value definitions to kvm_arm.h Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 13/44] KVM: arm64: Clarify rationale for ZCR_EL1 value restored on guest exit Fuad Tabba
2024-03-28 18:53 ` Mark Brown
2024-04-08 13:34 ` Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 14/44] KVM: arm64: Refactor calculating SVE state size to use helpers Fuad Tabba
2024-03-28 18:57 ` Mark Brown
2024-04-08 13:35 ` Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 15/44] KVM: arm64: Use active guest SVE vector length on guest restore Fuad Tabba
2024-03-28 19:17 ` Mark Brown
2024-04-09 9:34 ` Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 16/44] KVM: arm64: Do not map the host fpsimd state to hyp in pKVM Fuad Tabba
2024-03-28 19:20 ` Mark Brown
2024-03-27 17:35 ` [PATCH v1 17/44] KVM: arm64: Move some kvm_psci functions to a shared header Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 18/44] KVM: arm64: Refactor reset_mpidr() to extract its computation Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 19/44] KVM: arm64: Refactor kvm_vcpu_enable_ptrauth() for hyp use Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 20/44] KVM: arm64: Refactor enter_exception64() Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 21/44] KVM: arm64: Add PC_UPDATE_REQ flags covering all PC updates Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 22/44] KVM: arm64: Add vcpu flag copy primitive Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 23/44] KVM: arm64: Introduce gfn_to_memslot_prot() Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 24/44] KVM: arm64: Do not use the hva in kvm_handle_guest_abort() Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 25/44] KVM: arm64: Introduce hyp_rwlock_t Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 26/44] KVM: arm64: Add atomics-based checking refcount implementation at EL2 Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 27/44] KVM: arm64: Use atomic refcount helpers for 'struct hyp_page::refcount' Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 28/44] KVM: arm64: Remove locking from EL2 allocation fast-paths Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 29/44] KVM: arm64: Reformat/beautify PTP hypercall documentation Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 30/44] KVM: arm64: Rename firmware pseudo-register documentation file Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 31/44] KVM: arm64: Document the KVM/arm64-specific calls in hypercalls.rst Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 32/44] KVM: arm64: Prevent kmemleak from accessing .hyp.data Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 33/44] KVM: arm64: Issue CMOs when tearing down guest s2 pages Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 34/44] KVM: arm64: Do not set the virtual timer offset for protected vCPUs Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 35/44] KVM: arm64: Fix comment for __pkvm_vcpu_init_traps() Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 36/44] KVM: arm64: Do not re-initialize the KVM lock Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 37/44] KVM: arm64: Check directly whether a vcpu is protected Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 38/44] KVM: arm64: Trap debug break and watch from guest Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 39/44] KVM: arm64: Restrict protected VM capabilities Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 40/44] KVM: arm64: Do not support MTE for protected VMs Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 41/44] KVM: arm64: Move pkvm_vcpu_init_traps() to hyp vcpu init Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 42/44] KVM: arm64: Fix initializing traps in protected mode Fuad Tabba
2024-03-27 17:35 ` [PATCH v1 43/44] KVM: arm64: Advertise GICv3 sysreg interface to protected guests Fuad Tabba
2024-03-27 17:35 ` Fuad Tabba [this message]
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