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From: Alexandru Elisei <alexandru.elisei@arm.com>
To: Will Deacon <will@kernel.org>, kvmarm@lists.cs.columbia.edu
Cc: Marc Zyngier <maz@kernel.org>,
	kernel-team@android.com, linux-arm-kernel@lists.infradead.org,
	Catalin Marinas <catalin.marinas@arm.com>
Subject: Re: [PATCH v3 02/21] KVM: arm64: Add stand-alone page-table walker infrastructure
Date: Fri, 28 Aug 2020 16:51:02 +0100	[thread overview]
Message-ID: <8afa26de-1839-7e5e-a324-351b241e0976@arm.com> (raw)
In-Reply-To: <20200825093953.26493-3-will@kernel.org>

Hi Will,

On 8/25/20 10:39 AM, Will Deacon wrote:
> [..]
> +static void kvm_set_table_pte(kvm_pte_t *ptep, kvm_pte_t *childp)
> +{
> +	kvm_pte_t old = *ptep, pte = kvm_phys_to_pte(__pa(childp));
> +
> +	pte |= FIELD_PREP(KVM_PTE_TYPE, KVM_PTE_TYPE_TABLE);
> +	pte |= KVM_PTE_VALID;
> +
> +	WARN_ON(kvm_pte_valid(old));
> +	smp_store_release(ptep, pte);
> +}
> +
> +static bool kvm_set_valid_leaf_pte(kvm_pte_t *ptep, u64 pa, kvm_pte_t attr,
> +				   u32 level)
> +{
> +	kvm_pte_t old = *ptep, pte = kvm_phys_to_pte(pa);
> +	u64 type = (level == KVM_PGTABLE_MAX_LEVELS - 1) ? KVM_PTE_TYPE_PAGE :
> +							   KVM_PTE_TYPE_BLOCK;
> +
> +	pte |= attr & (KVM_PTE_LEAF_ATTR_LO | KVM_PTE_LEAF_ATTR_HI);
> +	pte |= FIELD_PREP(KVM_PTE_TYPE, type);
> +	pte |= KVM_PTE_VALID;
> +
> +	/* Tolerate KVM recreating the exact same mapping. */
> +	if (kvm_pte_valid(old))
> +		return old == pte;
> +
> +	smp_store_release(ptep, pte);
> +	return true;
> +}

These two functions look inconsistent to me - we refuse to update a valid leaf
entry with a new value, but we allow updating a valid table. Is there something
that I'm not taking into account?

Thanks,

Alex

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  parent reply	other threads:[~2020-08-28 15:50 UTC|newest]

Thread overview: 86+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-25  9:39 [PATCH v3 00/21] KVM: arm64: Rewrite page-table code and fault handling Will Deacon
2020-08-25  9:39 ` [PATCH v3 01/21] KVM: arm64: Remove kvm_mmu_free_memory_caches() Will Deacon
2020-08-25  9:39 ` [PATCH v3 02/21] KVM: arm64: Add stand-alone page-table walker infrastructure Will Deacon
2020-08-27 16:27   ` Alexandru Elisei
2020-08-28 15:43     ` Alexandru Elisei
2020-09-02 10:36     ` Will Deacon
2020-08-28 15:51   ` Alexandru Elisei [this message]
2020-09-02 10:49     ` Will Deacon
2020-09-02  6:31   ` Gavin Shan
2020-09-02 11:02     ` Will Deacon
2020-09-03  1:11       ` Gavin Shan
2020-08-25  9:39 ` [PATCH v3 03/21] KVM: arm64: Add support for creating kernel-agnostic stage-1 page tables Will Deacon
2020-08-28 15:35   ` Alexandru Elisei
2020-09-02 10:06     ` Will Deacon
2020-08-25  9:39 ` [PATCH v3 04/21] KVM: arm64: Use generic allocator for hyp stage-1 page-tables Will Deacon
2020-08-28 16:32   ` Alexandru Elisei
2020-09-02 11:35     ` Will Deacon
2020-09-02 14:48       ` Alexandru Elisei
2020-08-25  9:39 ` [PATCH v3 05/21] KVM: arm64: Add support for creating kernel-agnostic stage-2 page tables Will Deacon
2020-09-02  6:40   ` Gavin Shan
2020-09-02 11:30     ` Will Deacon
2020-08-25  9:39 ` [PATCH v3 06/21] KVM: arm64: Add support for stage-2 map()/unmap() in generic page-table Will Deacon
2020-09-01 16:24   ` Alexandru Elisei
2020-09-02 11:46     ` Will Deacon
2020-09-03  2:57   ` Gavin Shan
2020-09-03  5:27     ` Gavin Shan
2020-09-03 11:18   ` Gavin Shan
2020-09-03 12:30     ` Will Deacon
2020-09-03 16:15       ` Will Deacon
2020-09-04  0:47         ` Gavin Shan
2020-08-25  9:39 ` [PATCH v3 07/21] KVM: arm64: Convert kvm_phys_addr_ioremap() to generic page-table API Will Deacon
2020-09-01 17:08   ` Alexandru Elisei
2020-09-02 11:48     ` Will Deacon
2020-09-03  3:57   ` Gavin Shan
2020-08-25  9:39 ` [PATCH v3 08/21] KVM: arm64: Convert kvm_set_spte_hva() " Will Deacon
2020-09-02 15:37   ` Alexandru Elisei
2020-09-03 16:37     ` Will Deacon
2020-09-03  4:13   ` Gavin Shan
2020-08-25  9:39 ` [PATCH v3 09/21] KVM: arm64: Convert unmap_stage2_range() " Will Deacon
2020-09-02 16:23   ` Alexandru Elisei
2020-09-02 18:44     ` Alexandru Elisei
2020-09-03 17:57     ` Will Deacon
2020-09-08 13:07       ` Alexandru Elisei
2020-09-09 10:57         ` Alexandru Elisei
2020-09-03  4:19   ` Gavin Shan
2020-08-25  9:39 ` [PATCH v3 10/21] KVM: arm64: Add support for stage-2 page-aging in generic page-table Will Deacon
2020-09-03  4:33   ` Gavin Shan
2020-09-03 16:48     ` Will Deacon
2020-09-04  1:01       ` Gavin Shan
2020-08-25  9:39 ` [PATCH v3 11/21] KVM: arm64: Convert page-aging and access faults to generic page-table API Will Deacon
2020-09-03  4:37   ` Gavin Shan
2020-08-25  9:39 ` [PATCH v3 12/21] KVM: arm64: Add support for stage-2 write-protect in generic page-table Will Deacon
2020-09-03  4:47   ` Gavin Shan
2020-08-25  9:39 ` [PATCH v3 13/21] KVM: arm64: Convert write-protect operation to generic page-table API Will Deacon
2020-09-03  4:48   ` Gavin Shan
2020-08-25  9:39 ` [PATCH v3 14/21] KVM: arm64: Add support for stage-2 cache flushing in generic page-table Will Deacon
2020-09-03  4:51   ` Gavin Shan
2020-08-25  9:39 ` [PATCH v3 15/21] KVM: arm64: Convert memslot cache-flushing code to generic page-table API Will Deacon
2020-09-03  4:52   ` Gavin Shan
2020-08-25  9:39 ` [PATCH v3 16/21] KVM: arm64: Add support for relaxing stage-2 perms in generic page-table code Will Deacon
2020-09-03  4:55   ` Gavin Shan
2020-08-25  9:39 ` [PATCH v3 17/21] KVM: arm64: Convert user_mem_abort() to generic page-table API Will Deacon
2020-09-03  6:05   ` Gavin Shan
2020-08-25  9:39 ` [PATCH v3 18/21] KVM: arm64: Check the pgt instead of the pgd when modifying page-table Will Deacon
2020-09-03  5:00   ` Gavin Shan
2020-08-25  9:39 ` [PATCH v3 19/21] KVM: arm64: Remove unused page-table code Will Deacon
2020-09-03  6:02   ` Gavin Shan
2020-08-25  9:39 ` [PATCH v3 20/21] KVM: arm64: Remove unused 'pgd' field from 'struct kvm_s2_mmu' Will Deacon
2020-09-03  5:07   ` Gavin Shan
2020-09-03 16:50     ` Will Deacon
2020-09-04  0:59       ` Gavin Shan
2020-09-04 10:02         ` Marc Zyngier
2020-08-25  9:39 ` [PATCH v3 21/21] KVM: arm64: Don't constrain maximum IPA size based on host configuration Will Deacon
2020-09-03  5:09   ` Gavin Shan
2020-08-27 16:26 ` [PATCH v3 00/21] KVM: arm64: Rewrite page-table code and fault handling Alexandru Elisei
2020-09-01 16:15   ` Will Deacon
2020-09-03  7:34 ` Gavin Shan
2020-09-03 11:13   ` Gavin Shan
2020-09-03 11:48     ` Gavin Shan
2020-09-03 12:16       ` Will Deacon
2020-09-04  0:51         ` Gavin Shan
2020-09-04 10:07           ` Marc Zyngier
2020-09-05  3:56             ` Gavin Shan
2020-09-05  9:33               ` Marc Zyngier
2020-09-07  9:27           ` Will Deacon
2020-09-03 18:52 ` Will Deacon

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