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Re: [PATCH v5 07/13] KVM: Add KVM_EXIT_MEMORY_ERROR exit
From: |
Sean Christopherson |
Subject: |
Re: [PATCH v5 07/13] KVM: Add KVM_EXIT_MEMORY_ERROR exit |
Date: |
Mon, 28 Mar 2022 22:33:37 +0000 |
On Thu, Mar 10, 2022, Chao Peng wrote:
> This new KVM exit allows userspace to handle memory-related errors. It
> indicates an error happens in KVM at guest memory range [gpa, gpa+size).
> The flags includes additional information for userspace to handle the
> error. Currently bit 0 is defined as 'private memory' where '1'
> indicates error happens due to private memory access and '0' indicates
> error happens due to shared memory access.
>
> After private memory is enabled, this new exit will be used for KVM to
> exit to userspace for shared memory <-> private memory conversion in
> memory encryption usage.
>
> In such usage, typically there are two kind of memory conversions:
> - explicit conversion: happens when guest explicitly calls into KVM to
> map a range (as private or shared), KVM then exits to userspace to
> do the map/unmap operations.
> - implicit conversion: happens in KVM page fault handler.
> * if the fault is due to a private memory access then causes a
> userspace exit for a shared->private conversion request when the
> page has not been allocated in the private memory backend.
> * If the fault is due to a shared memory access then causes a
> userspace exit for a private->shared conversion request when the
> page has already been allocated in the private memory backend.
>
> Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com>
> Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com>
> ---
> Documentation/virt/kvm/api.rst | 22 ++++++++++++++++++++++
> include/uapi/linux/kvm.h | 9 +++++++++
> 2 files changed, 31 insertions(+)
>
> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
> index f76ac598606c..bad550c2212b 100644
> --- a/Documentation/virt/kvm/api.rst
> +++ b/Documentation/virt/kvm/api.rst
> @@ -6216,6 +6216,28 @@ array field represents return values. The userspace
> should update the return
> values of SBI call before resuming the VCPU. For more details on RISC-V SBI
> spec refer, https://github.com/riscv/riscv-sbi-doc.
>
> +::
> +
> + /* KVM_EXIT_MEMORY_ERROR */
> + struct {
> + #define KVM_MEMORY_EXIT_FLAG_PRIVATE (1 << 0)
> + __u32 flags;
> + __u32 padding;
> + __u64 gpa;
> + __u64 size;
> + } memory;
> +If exit reason is KVM_EXIT_MEMORY_ERROR then it indicates that the VCPU has
Doh, I'm pretty sure I suggested KVM_EXIT_MEMORY_ERROR. Any objection to using
KVM_EXIT_MEMORY_FAULT instead of KVM_EXIT_MEMORY_ERROR? "ERROR" makes me think
of ECC errors, i.e. uncorrected #MC in x86 land, not more generic "faults".
That
would align nicely with -EFAULT.
> +encountered a memory error which is not handled by KVM kernel module and
> +userspace may choose to handle it. The 'flags' field indicates the memory
> +properties of the exit.
- [PATCH v5 03/13] mm/shmem: Support memfile_notifier, (continued)
- [PATCH v5 03/13] mm/shmem: Support memfile_notifier, Chao Peng, 2022/03/10
- [PATCH v5 04/13] mm/shmem: Restrict MFD_INACCESSIBLE memory against RLIMIT_MEMLOCK, Chao Peng, 2022/03/10
- [PATCH v5 05/13] KVM: Extend the memslot to support fd-based private memory, Chao Peng, 2022/03/10
- [PATCH v5 06/13] KVM: Use kvm_userspace_memory_region_ext, Chao Peng, 2022/03/10
- [PATCH v5 07/13] KVM: Add KVM_EXIT_MEMORY_ERROR exit, Chao Peng, 2022/03/10
- Re: [PATCH v5 07/13] KVM: Add KVM_EXIT_MEMORY_ERROR exit,
Sean Christopherson <=
- [PATCH v5 08/13] KVM: Use memfile_pfn_ops to obtain pfn for private pages, Chao Peng, 2022/03/10
- [PATCH v5 10/13] KVM: Register private memslot to memory backing store, Chao Peng, 2022/03/10
- [PATCH v5 09/13] KVM: Handle page fault for private memory, Chao Peng, 2022/03/10
- [PATCH v5 12/13] KVM: Expose KVM_MEM_PRIVATE, Chao Peng, 2022/03/10
- [PATCH v5 11/13] KVM: Zap existing KVM mappings when pages changed in the private fd, Chao Peng, 2022/03/10