From: Will Deacon <will@kernel.org>
To: Fuad Tabba <tabba@google.com>
Cc: Andrew Jones <drjones@redhat.com>,
kvmarm@lists.cs.columbia.edu, maz@kernel.org,
james.morse@arm.com, alexandru.elisei@arm.com,
suzuki.poulose@arm.com, mark.rutland@arm.com,
christoffer.dall@arm.com, pbonzini@redhat.com,
qperret@google.com, kvm@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, kernel-team@android.com
Subject: Re: [PATCH v3 06/15] KVM: arm64: Restore mdcr_el2 from vcpu
Date: Thu, 12 Aug 2021 09:46:01 +0100 [thread overview]
Message-ID: <20210812084600.GA5912@willie-the-truck> (raw)
In-Reply-To: <CA+EHjTweLPu+DQ8hR9kEW0LrawtaoAoXR_+HmSEZpP-XOEm2qg@mail.gmail.com>
On Wed, Jul 21, 2021 at 08:37:21AM +0100, Fuad Tabba wrote:
> On Tue, Jul 20, 2021 at 3:53 PM Andrew Jones <drjones@redhat.com> wrote:
> >
> > On Mon, Jul 19, 2021 at 05:03:37PM +0100, Fuad Tabba wrote:
> > > On deactivating traps, restore the value of mdcr_el2 from the
> > > newly created and preserved host value vcpu context, rather than
> > > directly reading the hardware register.
> > >
> > > Up until and including this patch the two values are the same,
> > > i.e., the hardware register and the vcpu one. A future patch will
> > > be changing the value of mdcr_el2 on activating traps, and this
> > > ensures that its value will be restored.
> > >
> > > No functional change intended.
> >
> > I'm probably missing something, but I can't convince myself that the host
> > will end up with the same mdcr_el2 value after deactivating traps after
> > this patch as before. We clearly now restore whatever we had when
> > activating traps (presumably whatever we configured at init_el2_state
> > time), but is that equivalent to what we had before with the masking and
> > ORing that this patch drops?
>
> You're right. I thought that these were actually being initialized to
> the same values, but having a closer look at the code the mdcr values
> are not the same as pre-patch. I will fix this.
Can you elaborate on the issue here, please? I was just looking at this
but aren't you now relying on __init_el2_debug to configure this, which
should be fine?
Will
_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2021-08-12 8:47 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-19 16:03 [PATCH v3 00/15] KVM: arm64: Fixed features for protected VMs Fuad Tabba
2021-07-19 16:03 ` [PATCH v3 01/15] KVM: arm64: placeholder to check if VM is protected Fuad Tabba
2021-08-12 8:58 ` Will Deacon
2021-08-12 9:22 ` Fuad Tabba
2021-07-19 16:03 ` [PATCH v3 02/15] KVM: arm64: Remove trailing whitespace in comment Fuad Tabba
2021-08-12 8:59 ` Will Deacon
2021-07-19 16:03 ` [PATCH v3 03/15] KVM: arm64: MDCR_EL2 is a 64-bit register Fuad Tabba
2021-07-19 16:03 ` [PATCH v3 04/15] KVM: arm64: Fix names of config register fields Fuad Tabba
2021-07-19 16:03 ` [PATCH v3 05/15] KVM: arm64: Refactor sys_regs.h,c for nVHE reuse Fuad Tabba
2021-07-20 13:38 ` [PATCH v3 05/15] KVM: arm64: Refactor sys_regs.h, c " Andrew Jones
2021-07-20 14:03 ` Fuad Tabba
2021-08-12 8:59 ` Will Deacon
2021-07-19 16:03 ` [PATCH v3 06/15] KVM: arm64: Restore mdcr_el2 from vcpu Fuad Tabba
2021-07-20 14:52 ` Andrew Jones
2021-07-21 7:37 ` Fuad Tabba
2021-08-12 8:46 ` Will Deacon [this message]
2021-08-12 9:28 ` Fuad Tabba
2021-08-12 9:49 ` Will Deacon
2021-07-19 16:03 ` [PATCH v3 07/15] KVM: arm64: Track value of cptr_el2 in struct kvm_vcpu_arch Fuad Tabba
2021-08-12 8:59 ` Will Deacon
2021-07-19 16:03 ` [PATCH v3 08/15] KVM: arm64: Add feature register flag definitions Fuad Tabba
2021-08-12 8:59 ` Will Deacon
2021-08-12 9:21 ` Fuad Tabba
2021-07-19 16:03 ` [PATCH v3 09/15] KVM: arm64: Add config register bit definitions Fuad Tabba
2021-08-12 8:59 ` Will Deacon
2021-07-19 16:03 ` [PATCH v3 10/15] KVM: arm64: Guest exit handlers for nVHE hyp Fuad Tabba
2021-08-03 15:32 ` Will Deacon
2021-07-19 16:03 ` [PATCH v3 11/15] KVM: arm64: Add trap handlers for protected VMs Fuad Tabba
2021-08-12 9:45 ` Will Deacon
2021-08-16 14:39 ` Fuad Tabba
2021-07-19 16:03 ` [PATCH v3 12/15] KVM: arm64: Move sanitized copies of CPU features Fuad Tabba
2021-08-12 9:46 ` Will Deacon
2021-07-19 16:03 ` [PATCH v3 13/15] KVM: arm64: Trap access to pVM restricted features Fuad Tabba
2021-08-12 9:53 ` Will Deacon
2021-07-19 16:03 ` [PATCH v3 14/15] KVM: arm64: Handle protected guests at 32 bits Fuad Tabba
2021-07-19 19:43 ` Oliver Upton
2021-07-21 8:39 ` Fuad Tabba
2021-08-12 9:57 ` Will Deacon
2021-08-12 13:08 ` Fuad Tabba
2021-07-19 16:03 ` [PATCH v3 15/15] KVM: arm64: Restrict protected VM capabilities Fuad Tabba
2021-08-12 9:59 ` Will Deacon
2021-08-16 14:40 ` Fuad Tabba
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210812084600.GA5912@willie-the-truck \
--to=will@kernel.org \
--cc=alexandru.elisei@arm.com \
--cc=christoffer.dall@arm.com \
--cc=drjones@redhat.com \
--cc=james.morse@arm.com \
--cc=kernel-team@android.com \
--cc=kvm@vger.kernel.org \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=mark.rutland@arm.com \
--cc=maz@kernel.org \
--cc=pbonzini@redhat.com \
--cc=qperret@google.com \
--cc=suzuki.poulose@arm.com \
--cc=tabba@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox