From: Quentin Perret <qperret@google.com>
To: Will Deacon <will@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
Alexandru Elisei <alexandru.elisei@arm.com>,
Suzuki K Poulose <suzuki.poulose@arm.com>,
Catalin Marinas <catalin.marinas@arm.com>,
linux-arm-kernel@lists.infradead.org,
kvmarm@lists.cs.columbia.edu, linux-kernel@vger.kernel.org,
kernel-team@android.com
Subject: Re: [PATCH v3 15/15] KVM: arm64: pkvm: Unshare guest structs during teardown
Date: Fri, 10 Dec 2021 14:48:53 +0000 [thread overview]
Message-ID: <YbNo1SBn7ZNf89qL@google.com> (raw)
In-Reply-To: <20211209112233.GD1912@willie-the-truck>
On Thursday 09 Dec 2021 at 11:22:33 (+0000), Will Deacon wrote:
> On Wed, Dec 01, 2021 at 05:04:09PM +0000, Quentin Perret wrote:
> > Make use of the newly introduced unshare hypercall during guest teardown
> > to unmap guest-related data structures from the hyp stage-1.
> >
> > Signed-off-by: Quentin Perret <qperret@google.com>
> > ---
> > arch/arm64/include/asm/kvm_host.h | 2 ++
> > arch/arm64/include/asm/kvm_mmu.h | 1 +
> > arch/arm64/kvm/arm.c | 2 ++
> > arch/arm64/kvm/fpsimd.c | 34 ++++++++++++++++++++++---
> > arch/arm64/kvm/mmu.c | 42 +++++++++++++++++++++++++++++++
> > arch/arm64/kvm/reset.c | 8 +++++-
> > 6 files changed, 85 insertions(+), 4 deletions(-)
>
> [...]
>
> > diff --git a/arch/arm64/kvm/mmu.c b/arch/arm64/kvm/mmu.c
> > index d72566896755..8e506ba8988e 100644
> > --- a/arch/arm64/kvm/mmu.c
> > +++ b/arch/arm64/kvm/mmu.c
> > @@ -344,6 +344,32 @@ static int share_pfn_hyp(u64 pfn)
> > return ret;
> > }
> >
> > +static int unshare_pfn_hyp(u64 pfn)
> > +{
> > + struct rb_node **node, *parent;
> > + struct hyp_shared_pfn *this;
> > + int ret = 0;
> > +
> > + mutex_lock(&hyp_shared_pfns_lock);
> > + this = find_shared_pfn(pfn, &node, &parent);
> > + if (WARN_ON(!this)) {
> > + ret = -EINVAL;
>
> -ENOENT?
Sure.
> > + goto unlock;
> > + }
> > +
> > + this->count--;
> > + if (this->count)
> > + goto unlock;
>
> Again, if we did an RCU lookup then this could be converted to a refcount_t
> to take the mutex only when it hits zero. But for now I think it's fine.
No objection to do this in the future, but yeah I think we might as well
start simple :)
> > +
> > + rb_erase(&this->node, &hyp_shared_pfns);
> > + kfree(this);
> > + ret = kvm_call_hyp_nvhe(__pkvm_host_unshare_hyp, pfn, 1);
> > +unlock:
> > + mutex_unlock(&hyp_shared_pfns_lock);
> > +
> > + return ret;
> > +}
> > +
> > int kvm_share_hyp(void *from, void *to)
> > {
> > phys_addr_t start, end, cur;
> > @@ -376,6 +402,22 @@ int kvm_share_hyp(void *from, void *to)
> > return 0;
> > }
> >
> > +void kvm_unshare_hyp(void *from, void *to)
> > +{
> > + phys_addr_t start, end, cur;
> > + u64 pfn;
> > +
> > + if (is_kernel_in_hyp_mode() || kvm_host_owns_hyp_mappings() || !from)
>
> I don't think you need the is_kernel_in_hyp_mode() check any more not that
> you've moved that into kvm_host_owns_hyp_mappings().
The logic is a little odd, but I think I still do as
kvm_host_owns_hyp_mappings() will return false if is_kernel_in_hyp_mode()
is true.
prev parent reply other threads:[~2021-12-10 14:49 UTC|newest]
Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-12-01 17:03 [PATCH v3 00/15] KVM: arm64: Introduce kvm_share_hyp() Quentin Perret
2021-12-01 17:03 ` [PATCH v3 01/15] KVM: arm64: Check if running in VHE from kvm_host_owns_hyp_mappings() Quentin Perret
2021-12-09 10:10 ` Will Deacon
2021-12-10 13:37 ` Quentin Perret
2021-12-01 17:03 ` [PATCH v3 02/15] KVM: arm64: Provide {get,put}_page() stubs for early hyp allocator Quentin Perret
2021-12-09 10:12 ` Will Deacon
2021-12-01 17:03 ` [PATCH v3 03/15] KVM: arm64: Refcount hyp stage-1 pgtable pages Quentin Perret
2021-12-09 10:29 ` Will Deacon
2021-12-10 14:34 ` Quentin Perret
2021-12-13 12:53 ` Will Deacon
2021-12-01 17:03 ` [PATCH v3 04/15] KVM: arm64: Fixup hyp stage-1 refcount Quentin Perret
2021-12-09 11:09 ` Will Deacon
2021-12-01 17:03 ` [PATCH v3 05/15] KVM: arm64: Hook up ->page_count() for hypervisor stage-1 page-table Quentin Perret
2021-12-01 17:04 ` [PATCH v3 06/15] KVM: arm64: Implement kvm_pgtable_hyp_unmap() at EL2 Quentin Perret
2021-12-07 14:47 ` Andrew Walbran
2021-12-08 9:51 ` Quentin Perret
2021-12-08 14:40 ` Andrew Walbran
2021-12-15 16:02 ` Quentin Perret
2021-12-01 17:04 ` [PATCH v3 07/15] KVM: arm64: Introduce kvm_share_hyp() Quentin Perret
2021-12-09 11:13 ` Will Deacon
2021-12-10 14:37 ` Quentin Perret
2021-12-01 17:04 ` [PATCH v3 08/15] KVM: arm64: pkvm: Refcount the pages shared with EL2 Quentin Perret
2021-12-09 11:16 ` Will Deacon
2021-12-01 17:04 ` [PATCH v3 09/15] KVM: arm64: Extend pkvm_page_state enumeration to handle absent pages Quentin Perret
2021-12-14 14:47 ` Andrew Walbran
2021-12-01 17:04 ` [PATCH v3 10/15] KVM: arm64: Introduce wrappers for host and hyp spin lock accessors Quentin Perret
2021-12-14 14:48 ` Andrew Walbran
2021-12-14 14:52 ` Will Deacon
2021-12-01 17:04 ` [PATCH v3 11/15] KVM: arm64: Implement do_share() helper for sharing memory Quentin Perret
2021-12-10 15:18 ` Andrew Walbran
2021-12-01 17:04 ` [PATCH v3 12/15] KVM: arm64: Implement __pkvm_host_share_hyp() using do_share() Quentin Perret
2021-12-01 17:04 ` [PATCH v3 13/15] KVM: arm64: Implement do_unshare() helper for unsharing memory Quentin Perret
2021-12-10 15:08 ` Andrew Walbran
2021-12-01 17:04 ` [PATCH v3 14/15] KVM: arm64: Expose unshare hypercall to the host Quentin Perret
2021-12-01 17:04 ` [PATCH v3 15/15] KVM: arm64: pkvm: Unshare guest structs during teardown Quentin Perret
2021-12-09 11:22 ` Will Deacon
2021-12-10 14:48 ` Quentin Perret [this message]
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=YbNo1SBn7ZNf89qL@google.com \
--to=qperret@google.com \
--cc=alexandru.elisei@arm.com \
--cc=catalin.marinas@arm.com \
--cc=james.morse@arm.com \
--cc=kernel-team@android.com \
--cc=kvmarm@lists.cs.columbia.edu \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=maz@kernel.org \
--cc=suzuki.poulose@arm.com \
--cc=will@kernel.org \
/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;
as well as URLs for NNTP newsgroup(s).