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Thu, 08 Aug 2024 05:00:02 -0700 (PDT) Received: from draig.lan ([85.9.250.243]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-36d27156c8asm1700288f8f.24.2024.08.08.05.00.01 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 08 Aug 2024 05:00:01 -0700 (PDT) Received: from draig (localhost [IPv6:::1]) by draig.lan (Postfix) with ESMTP id 751635F769; Thu, 8 Aug 2024 13:00:00 +0100 (BST) From: =?utf-8?Q?Alex_Benn=C3=A9e?= To: Sean Christopherson Cc: Paolo Bonzini , Marc Zyngier , Oliver Upton , Tianrui Zhao , Bibo Mao , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Christian Borntraeger , Janosch Frank , Claudio Imbrenda , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, David Matlack , David Stevens Subject: Re: [PATCH v12 13/84] KVM: Annotate that all paths in hva_to_pfn() might sleep In-Reply-To: <20240726235234.228822-14-seanjc@google.com> (Sean Christopherson's message of "Fri, 26 Jul 2024 16:51:22 -0700") References: <20240726235234.228822-1-seanjc@google.com> <20240726235234.228822-14-seanjc@google.com> Date: Thu, 08 Aug 2024 13:00:00 +0100 Message-ID: <87bk23ql6n.fsf@draig.linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240808_050005_183668_7783D257 X-CRM114-Status: GOOD ( 16.69 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Sean Christopherson writes: > Now that hva_to_pfn() no longer supports being called in atomic context, > move the might_sleep() annotation from hva_to_pfn_slow() to > hva_to_pfn(). The commentary for hva_to_pfn_fast disagrees. /* * The fast path to get the writable pfn which will be stored in @pfn, * true indicates success, otherwise false is returned. It's also the * only part that runs if we can in atomic context. */ static bool hva_to_pfn_fast(struct kvm_follow_pfn *kfp, kvm_pfn_t *pfn) At which point did it loose the ability to run in the atomic context? I couldn't work it out from the commits. > > Signed-off-by: Sean Christopherson > --- > virt/kvm/kvm_main.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 84c73b4fc804..03af1a0090b1 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -2807,8 +2807,6 @@ static int hva_to_pfn_slow(unsigned long addr, bool= *async, bool write_fault, > struct page *page; > int npages; >=20=20 > - might_sleep(); > - > if (writable) > *writable =3D write_fault; >=20=20 > @@ -2947,6 +2945,8 @@ kvm_pfn_t hva_to_pfn(unsigned long addr, bool inter= ruptible, bool *async, > kvm_pfn_t pfn; > int npages, r; >=20=20 > + might_sleep(); > + > if (hva_to_pfn_fast(addr, write_fault, writable, &pfn)) > return pfn; --=20 Alex Benn=C3=A9e Virtualisation Tech Lead @ Linaro