From: Andrew Walbran <qwandor@google.com>
To: Quentin Perret <qperret@google.com>
Cc: kernel-team@android.com, Marc Zyngier <maz@kernel.org>,
linux-kernel@vger.kernel.org,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <will@kernel.org>,
kvmarm@lists.cs.columbia.edu,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v3 10/15] KVM: arm64: Introduce wrappers for host and hyp spin lock accessors
Date: Tue, 14 Dec 2021 14:48:30 +0000 [thread overview]
Message-ID: <CA+_y_2HKwtm5839QyEY9D8PaZWky_Zvn3msrw2gcR2Z7UZgObQ@mail.gmail.com> (raw)
In-Reply-To: <20211201170411.1561936-11-qperret@google.com>
On Wed, 1 Dec 2021 at 17:04, 'Quentin Perret' via kernel-team
<kernel-team@android.com> wrote:
>
> From: Will Deacon <will@kernel.org>
>
> In preparation for adding additional locked sections for manipulating
> page-tables at EL2, introduce some simple wrappers around the host and
> hypervisor locks so that it's a bit easier to read and bit more difficult
> to take the wrong lock (or even take them in the wrong order).
Looks good, but how does this help prevent taking locks in the wrong order?
>
> Signed-off-by: Will Deacon <will@kernel.org>
> Signed-off-by: Quentin Perret <qperret@google.com>
> ---
> arch/arm64/kvm/hyp/nvhe/mem_protect.c | 32 ++++++++++++++++++++++-----
> 1 file changed, 26 insertions(+), 6 deletions(-)
>
> diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> index c1a90dd022b8..757dfefe3aeb 100644
> --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
> @@ -27,6 +27,26 @@ static struct hyp_pool host_s2_pool;
>
> const u8 pkvm_hyp_id = 1;
>
> +static void host_lock_component(void)
> +{
> + hyp_spin_lock(&host_kvm.lock);
> +}
> +
> +static void host_unlock_component(void)
> +{
> + hyp_spin_unlock(&host_kvm.lock);
> +}
> +
> +static void hyp_lock_component(void)
> +{
> + hyp_spin_lock(&pkvm_pgd_lock);
> +}
> +
> +static void hyp_unlock_component(void)
> +{
> + hyp_spin_unlock(&pkvm_pgd_lock);
> +}
> +
> static void *host_s2_zalloc_pages_exact(size_t size)
> {
> void *addr = hyp_alloc_pages(&host_s2_pool, get_order(size));
> @@ -338,14 +358,14 @@ static int host_stage2_idmap(u64 addr)
>
> prot = is_memory ? PKVM_HOST_MEM_PROT : PKVM_HOST_MMIO_PROT;
>
> - hyp_spin_lock(&host_kvm.lock);
> + host_lock_component();
> ret = host_stage2_adjust_range(addr, &range);
> if (ret)
> goto unlock;
>
> ret = host_stage2_idmap_locked(range.start, range.end - range.start, prot);
> unlock:
> - hyp_spin_unlock(&host_kvm.lock);
> + host_unlock_component();
>
> return ret;
> }
> @@ -369,8 +389,8 @@ int __pkvm_host_share_hyp(u64 pfn)
> if (!addr_is_memory(addr))
> return -EINVAL;
>
> - hyp_spin_lock(&host_kvm.lock);
> - hyp_spin_lock(&pkvm_pgd_lock);
> + host_lock_component();
> + hyp_lock_component();
>
> ret = kvm_pgtable_get_leaf(&host_kvm.pgt, addr, &pte, NULL);
> if (ret)
> @@ -432,8 +452,8 @@ int __pkvm_host_share_hyp(u64 pfn)
> BUG_ON(ret);
>
> unlock:
> - hyp_spin_unlock(&pkvm_pgd_lock);
> - hyp_spin_unlock(&host_kvm.lock);
> + hyp_unlock_component();
> + host_unlock_component();
>
> return ret;
> }
> --
> 2.34.0.rc2.393.gf8c9666880-goog
>
> --
> To unsubscribe from this group and stop receiving emails from it, send an email to kernel-team+unsubscribe@android.com.
>
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next prev parent reply other threads:[~2021-12-14 14:48 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 ` [PATCH v3 02/15] KVM: arm64: Provide {get,put}_page() " 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 [this message]
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
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