From: Vipin Sharma <vipinsh@google.com>
To: maz@kernel.org, oliver.upton@linux.dev, james.morse@arm.com,
suzuki.poulose@arm.com, yuzenghui@huawei.com,
catalin.marinas@arm.com, will@kernel.org, chenhuacai@kernel.org,
aleksandar.qemu.devel@gmail.com, tsbogend@alpha.franken.de,
anup@brainfault.org, atishp@atishpatra.org,
paul.walmsley@sifive.com, palmer@dabbelt.com,
aou@eecs.berkeley.edu, seanjc@google.com, pbonzini@redhat.com,
dmatlack@google.com, ricarkol@google.com
Cc: linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev,
linux-mips@vger.kernel.org, kvm-riscv@lists.infradead.org,
linux-riscv@lists.infradead.org, linux-kselftest@vger.kernel.org,
kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
Vipin Sharma <vipinsh@google.com>
Subject: [PATCH v2 09/16] KVM: arm64: Document the page table walker actions based on the callback's return value
Date: Fri, 2 Jun 2023 09:09:07 -0700 [thread overview]
Message-ID: <20230602160914.4011728-10-vipinsh@google.com> (raw)
In-Reply-To: <20230602160914.4011728-1-vipinsh@google.com>
Document what the page table walker do when walker callback function returns
a value.
Current documentation is not correct as negative error of -EAGAIN on a
non-shared page table walker doesn't terminate the walker and continues
to the next step.
There might be a better place to keep this information, for now this
documentation will work as a reference guide until a better way is
found.
Signed-off-by: Vipin Sharma <vipinsh@google.com>
---
arch/arm64/include/asm/kvm_pgtable.h | 15 +++++++++++++--
1 file changed, 13 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/include/asm/kvm_pgtable.h b/arch/arm64/include/asm/kvm_pgtable.h
index 8ef7e8f3f054..957bc20dab00 100644
--- a/arch/arm64/include/asm/kvm_pgtable.h
+++ b/arch/arm64/include/asm/kvm_pgtable.h
@@ -711,8 +711,19 @@ int kvm_pgtable_stage2_split(struct kvm_pgtable *pgt, u64 addr, u64 size,
* after invoking the walker callback, allowing the walker to descend into
* a newly installed table.
*
- * Returning a negative error code from the walker callback function will
- * terminate the walk immediately with the same error code.
+ * Depending on the return value from the walker callback function, the page
+ * table walk will continue or exit the walk. This is also dependent on the
+ * type of the walker, i.e. shared walker (vCPU fault handlers) or non-shared
+ * walker.
+ *
+ * Walker Type | Callback | Walker action
+ * -------------|------------------|--------------
+ * Non-Shared | 0 | Continue
+ * Non-Shared | -EAGAIN | Continue
+ * Non-Shared | Any other | Exit
+ * -------------|------------------|--------------
+ * Shared | 0 | Continue
+ * Shared | Any other | Exit
*
* Return: 0 on success, negative error code on failure.
*/
--
2.41.0.rc0.172.g3f132b7071-goog
next prev parent reply other threads:[~2023-06-02 16:10 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-02 16:08 [PATCH v2 00/16] Use MMU read lock for clear-dirty-log Vipin Sharma
2023-06-02 16:08 ` [PATCH v2 01/16] KVM: selftests: Clear dirty logs in user defined chunks sizes in dirty_log_perf_test Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 02/16] KVM: selftests: Add optional delay between consecutive clear-dirty-log calls Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 03/16] KVM: selftests: Pass the count of read and write accesses from guest to host Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 04/16] KVM: selftests: Print read-write progress by vCPUs in dirty_log_perf_test Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 05/16] KVM: selftests: Allow independent execution of " Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 06/16] KVM: arm64: Correct the kvm_pgtable_stage2_flush() documentation Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 07/16] KVM: mmu: Move mmu lock/unlock to arch code for clear dirty log Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 08/16] KMV: arm64: Pass page table walker flags to stage2_apply_range_*() Vipin Sharma
2023-06-02 16:09 ` Vipin Sharma [this message]
2023-06-05 14:35 ` [PATCH v2 09/16] KVM: arm64: Document the page table walker actions based on the callback's return value Zhi Wang
2023-06-06 17:30 ` Vipin Sharma
2023-06-07 12:37 ` Zhi Wang
2023-06-08 20:17 ` Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 10/16] KVM: arm64: Return -ENOENT if PTE is not valid in stage2_attr_walker Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 11/16] KVM: arm64: Use KVM_PGTABLE_WALK_SHARED flag instead of KVM_PGTABLE_WALK_HANDLE_FAULT Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 12/16] KVM: arm64: Retry shared page table walks outside of fault handler Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 13/16] KVM: arm64: Run clear-dirty-log under MMU read lock Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 14/16] KVM: arm64: Pass page walker flags from callers of stage 2 split walker Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 15/16] KVM: arm64: Provide option to pass page walker flag for huge page splits Vipin Sharma
2023-06-02 16:09 ` [PATCH v2 16/16] KVM: arm64: Split huge pages during clear-dirty-log under MMU read lock Vipin Sharma
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