From: Marc Zyngier <maz@kernel.org>
To: Andrew Jones <drjones@redhat.com>
Cc: linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
linux-kernel@vger.kernel.org, kernel-team@android.com,
Srivatsa Vaddagiri <vatsa@codeaurora.org>,
Shanker R Donthineni <sdonthineni@nvidia.com>,
will@kernel.org
Subject: Re: [PATCH 10/16] KVM: arm64: Add some documentation for the MMIO guard feature
Date: Fri, 23 Jul 2021 14:30:13 +0100 [thread overview]
Message-ID: <60d8e9e95ee4640cf3b457c53cb4cc7a@kernel.org> (raw)
In-Reply-To: <20210721211743.hb2cxghhwl2y22yh@gator>
On 2021-07-21 22:17, Andrew Jones wrote:
> On Thu, Jul 15, 2021 at 05:31:53PM +0100, Marc Zyngier wrote:
>> Document the hypercalls user for the MMIO guard infrastructure.
>>
>> Signed-off-by: Marc Zyngier <maz@kernel.org>
>> ---
>> Documentation/virt/kvm/arm/index.rst | 1 +
>> Documentation/virt/kvm/arm/mmio-guard.rst | 73
>> +++++++++++++++++++++++
>> 2 files changed, 74 insertions(+)
>> create mode 100644 Documentation/virt/kvm/arm/mmio-guard.rst
>>
>> diff --git a/Documentation/virt/kvm/arm/index.rst
>> b/Documentation/virt/kvm/arm/index.rst
>> index 78a9b670aafe..e77a0ee2e2d4 100644
>> --- a/Documentation/virt/kvm/arm/index.rst
>> +++ b/Documentation/virt/kvm/arm/index.rst
>> @@ -11,3 +11,4 @@ ARM
>> psci
>> pvtime
>> ptp_kvm
>> + mmio-guard
>> diff --git a/Documentation/virt/kvm/arm/mmio-guard.rst
>> b/Documentation/virt/kvm/arm/mmio-guard.rst
>> new file mode 100644
>> index 000000000000..a5563a3e12cc
>> --- /dev/null
>> +++ b/Documentation/virt/kvm/arm/mmio-guard.rst
>> @@ -0,0 +1,73 @@
>> +.. SPDX-License-Identifier: GPL-2.0
>> +
>> +==============
>> +KVM MMIO guard
>> +==============
>> +
>> +KVM implements device emulation by handling translation faults to any
>> +IPA range that is not contained a memory slot. Such translation fault
> ^ in ^ a
>
>> +is in most cases passed on to userspace (or in rare cases to the host
>> +kernel) with the address, size and possibly data of the access for
>> +emulation.
>> +
>> +Should the guest exit with an address that is not one that
>> corresponds
>> +to an emulatable device, userspace may take measures that are not the
>> +most graceful as far as the guest is concerned (such as terminating
>> it
>> +or delivering a fatal exception).
>> +
>> +There is also an element of trust: by forwarding the request to
>> +userspace, the kernel asumes that the guest trusts userspace to do
>> the
>
> assumes
>
>> +right thing.
>> +
>> +The KVM MMIO guard offers a way to mitigate this last point: a guest
>> +can request that only certainly regions of the IPA space are valid as
>
> certain
Thanks, all corrections applied.
>
>> +MMIO. Only these regions will be handled as an MMIO, and any other
>> +will result in an exception being delivered to the guest.
>> +
>> +This relies on a set of hypercalls defined in the KVM-specific range,
>> +using the HVC64 calling convention.
>> +
>> +* ARM_SMCCC_KVM_FUNC_MMIO_GUARD_INFO
>> +
>> + ============== ======== ================================
>> + Function ID: (uint32) 0xC6000002
>> + Arguments: none
>> + Return Values: (int64) NOT_SUPPORTED(-1) on error, or
>> + (uint64) Protection Granule (PG) size in
>> + bytes (r0)
>> + ============== ======== ================================
>> +
>> +* ARM_SMCCC_KVM_FUNC_MMIO_GUARD_ENROLL
>> +
>> + ============== ======== ==============================
>> + Function ID: (uint32) 0xC6000003
>> + Arguments: none
>> + Return Values: (int64) NOT_SUPPORTED(-1) on error, or
>> + RET_SUCCESS(0) (r0)
>> + ============== ======== ==============================
>> +
>> +* ARM_SMCCC_KVM_FUNC_MMIO_GUARD_MAP
>> +
>> + ============== ========
>> ======================================
>> + Function ID: (uint32) 0xC6000004
>> + Arguments: (uint64) The base of the PG-sized IPA range
>> + that is allowed to be accessed as
>> + MMIO. Must aligned to the PG size (r1)
>
> align
Hmmm. Ugly mix of tab and spaces. I have no idea what the norm
is here, so I'll just put spaces. I'm sure someone will let me
know if I'm wrong! ;-)
>
>> + (uint64) Index in the MAIR_EL1 register
>> + providing the memory attribute that
>> + is used by the guest (r2)
>> + Return Values: (int64) NOT_SUPPORTED(-1) on error, or
>> + RET_SUCCESS(0) (r0)
>> + ============== ========
>> ======================================
>> +
>> +* ARM_SMCCC_KVM_FUNC_MMIO_GUARD_UNMAP
>> +
>> + ============== ========
>> ======================================
>> + Function ID: (uint32) 0xC6000004
>
> copy+paste error, should be 0xC6000005
Gah, well cpotted.
>
>> + Arguments: (uint64) The base of the PG-sized IPA range
>> + that is forbidden to be accessed as
>
> is now forbidden
>
> or
>
> was allowed
>
> or just drop that part of the sentence because its covered by the "and
> have been previously mapped" part. Something like
>
> PG-sized IPA range aligned to the PG size which has been previously
> mapped
> (r1)
Picked the latter.
Thanks again,
M.
--
Jazz is not dead. It just smells funny...
next prev parent reply other threads:[~2021-07-23 13:30 UTC|newest]
Thread overview: 62+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-15 16:31 [PATCH 00/16] KVM: arm64: MMIO guard PV services Marc Zyngier
2021-07-15 16:31 ` [PATCH 01/16] KVM: arm64: Generalise VM features into a set of flags Marc Zyngier
2021-07-27 18:10 ` Will Deacon
2021-07-28 9:41 ` Marc Zyngier
2021-07-28 14:51 ` Steven Price
2021-07-15 16:31 ` [PATCH 02/16] KVM: arm64: Don't issue CMOs when the physical address is invalid Marc Zyngier
2021-07-19 17:18 ` Quentin Perret
2021-07-20 8:04 ` Marc Zyngier
2021-07-27 18:10 ` Will Deacon
2021-07-28 9:45 ` Marc Zyngier
2021-07-15 16:31 ` [PATCH 03/16] KVM: arm64: Turn kvm_pgtable_stage2_set_owner into kvm_pgtable_stage2_annotate Marc Zyngier
2021-07-20 10:09 ` Quentin Perret
2021-07-20 10:21 ` Marc Zyngier
2021-07-20 10:38 ` Quentin Perret
2021-07-20 11:20 ` Marc Zyngier
2021-07-20 11:36 ` Quentin Perret
2021-07-20 13:13 ` Marc Zyngier
2021-07-15 16:31 ` [PATCH 04/16] KVM: arm64: Add MMIO checking infrastructure Marc Zyngier
2021-07-20 11:13 ` Quentin Perret
2021-07-20 13:15 ` Marc Zyngier
2021-07-20 15:49 ` Quentin Perret
2021-07-22 18:04 ` Marc Zyngier
2021-07-23 10:16 ` Quentin Perret
2021-07-27 18:11 ` Will Deacon
2021-07-28 9:57 ` Marc Zyngier
2021-07-30 12:26 ` Will Deacon
2021-07-30 13:04 ` Marc Zyngier
2021-07-30 12:58 ` Quentin Perret
2021-07-15 16:31 ` [PATCH 05/16] KVM: arm64: Plumb MMIO checking into the fault handling Marc Zyngier
2021-07-27 18:11 ` Will Deacon
2021-07-28 10:21 ` Marc Zyngier
2021-07-30 12:38 ` Will Deacon
2021-07-15 16:31 ` [PATCH 06/16] KVM: arm64: Force a full unmap on vpcu reinit Marc Zyngier
2021-07-27 18:11 ` Will Deacon
2021-07-28 10:38 ` Marc Zyngier
2021-07-30 12:50 ` Will Deacon
2021-07-15 16:31 ` [PATCH 07/16] KVM: arm64: Wire MMIO guard hypercalls Marc Zyngier
2021-07-27 18:11 ` Will Deacon
2021-07-28 10:47 ` Marc Zyngier
2021-07-30 13:11 ` Will Deacon
2021-08-01 11:20 ` Marc Zyngier
2021-07-15 16:31 ` [PATCH 08/16] KVM: arm64: Add tracepoint for failed MMIO guard check Marc Zyngier
2021-07-15 16:31 ` [PATCH 09/16] KVM: arm64: Advertise a capability for MMIO guard Marc Zyngier
2021-07-15 16:31 ` [PATCH 10/16] KVM: arm64: Add some documentation for the MMIO guard feature Marc Zyngier
2021-07-21 21:17 ` Andrew Jones
2021-07-23 13:30 ` Marc Zyngier [this message]
2021-07-23 13:38 ` Andrew Jones
2021-07-23 13:52 ` Marc Zyngier
2021-07-15 16:31 ` [PATCH 11/16] firmware/smccc: Call arch-specific hook on discovering KVM services Marc Zyngier
2021-07-15 16:31 ` [PATCH 12/16] mm/ioremap: Add arch-specific callbacks on ioremap/iounmap calls Marc Zyngier
2021-07-27 18:12 ` Will Deacon
2021-07-28 11:01 ` Marc Zyngier
2021-07-30 14:07 ` Will Deacon
2021-07-15 16:31 ` [PATCH 13/16] arm64: Implement ioremap/iounmap hooks calling into KVM's MMIO guard Marc Zyngier
2021-07-15 16:31 ` [PATCH 14/16] arm64: Enroll into KVM's MMIO guard if required Marc Zyngier
2021-07-15 16:31 ` [PATCH 15/16] arm64: Add a helper to retrieve the PTE of a fixmap Marc Zyngier
2021-07-20 11:16 ` Quentin Perret
2021-07-15 16:31 ` [PATCH 16/16] arm64: Register earlycon fixmap with the MMIO guard Marc Zyngier
2021-07-21 21:42 ` [PATCH 00/16] KVM: arm64: MMIO guard PV services Andrew Jones
2021-07-22 10:00 ` Marc Zyngier
2021-07-22 13:25 ` Andrew Jones
2021-07-22 15:30 ` Marc Zyngier
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