From: Paolo Bonzini <pbonzini@redhat.com>
To: Chia-I Wu <olvaffe@gmail.com>, kvm@vger.kernel.org
Cc: wanpengli@tencent.com, joro@8bytes.org,
dri-devel@lists.freedesktop.org, gurchetansingh@chromium.org,
kraxel@redhat.com, vkuznets@redhat.com, jmattson@google.com
Subject: Re: [RFC PATCH 0/3] KVM: x86: honor guest memory type
Date: Thu, 13 Feb 2020 22:41:22 +0100 [thread overview]
Message-ID: <8fdb85ea-6441-9519-ae35-eaf91ffe8741@redhat.com> (raw)
In-Reply-To: <20200213213036.207625-1-olvaffe@gmail.com>
On 13/02/20 22:30, Chia-I Wu wrote:
> Hi,
>
> Host GPU drivers like to give userspace WC mapping. When the userspace makes
> the mapping available to a guest, it also tells the guest to create a WC
> mapping. However, even when the guest kernel picks the correct memory type,
> it gets ignored because of VMX_EPT_IPAT_BIT on Intel.
>
> This series adds a new flag to KVM_SET_USER_MEMORY_REGION, which tells the
> host kernel to honor the guest memory type for the memslot. An alternative
> fix is for KVM to unconditionally honor the guest memory type (unless it is
> MMIO, to avoid MCEs on Intel). I believe the alternative fix is how things
> are on ARM, and probably also how things are on AMD.
>
> I am new to KVM and HW virtualization technologies. This series is meant as
> an RFC.
>
When we tried to do this in the past, we got machine checks everywhere
unfortunately due to the same address being mapped with different memory
types. Unfortunately I cannot find the entry anymore in bugzilla, but
this was not fixed as far as I know.
Paolo
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next prev parent reply other threads:[~2020-02-13 21:41 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-13 21:30 [RFC PATCH 0/3] KVM: x86: honor guest memory type Chia-I Wu
2020-02-13 21:30 ` [RFC PATCH 1/3] KVM: vmx: rewrite the comment in vmx_get_mt_mask Chia-I Wu
2020-02-14 9:36 ` Paolo Bonzini
2020-02-13 21:30 ` [RFC PATCH 2/3] RFC: KVM: add KVM_MEM_DMA Chia-I Wu
2020-02-13 21:30 ` [RFC PATCH 3/3] RFC: KVM: x86: support KVM_CAP_DMA_MEM Chia-I Wu
2020-02-13 21:41 ` Paolo Bonzini [this message]
2020-02-13 22:18 ` [RFC PATCH 0/3] KVM: x86: honor guest memory type Chia-I Wu
2020-02-14 10:26 ` Paolo Bonzini
2020-02-14 19:52 ` Sean Christopherson
2020-02-14 21:47 ` Chia-I Wu
2020-02-14 21:56 ` Jim Mattson
2020-02-14 22:03 ` Sean Christopherson
2020-02-18 16:28 ` Paolo Bonzini
2020-02-18 22:58 ` Sean Christopherson
2020-02-19 9:52 ` Tian, Kevin
2020-02-19 19:36 ` Chia-I Wu
2020-02-20 2:04 ` Tian, Kevin
2020-02-20 2:38 ` Tian, Kevin
2020-02-20 22:23 ` Chia-I Wu
2020-02-21 0:23 ` Tian, Kevin
2020-02-21 4:45 ` Chia-I Wu
2020-02-21 4:51 ` Chia-I Wu
2020-02-21 5:39 ` Tian, Kevin
2020-02-21 15:59 ` Sean Christopherson
2020-02-21 18:21 ` Chia-I Wu
2020-02-25 1:29 ` Tian, Kevin
2020-02-14 21:15 ` Chia-I Wu
2020-02-19 10:00 ` Tian, Kevin
2020-02-19 19:18 ` Chia-I Wu
2020-02-20 2:13 ` Tian, Kevin
2020-02-20 23:02 ` Chia-I Wu
2020-02-24 10:57 ` Gerd Hoffmann
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