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Thu, 10 Oct 2024 11:25:20 -0700 (PDT) Reply-To: Sean Christopherson Date: Thu, 10 Oct 2024 11:23:16 -0700 In-Reply-To: <20241010182427.1434605-1-seanjc@google.com> X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Post: List-Subscribe: , , List-Unsubscribe: Mime-Version: 1.0 References: <20241010182427.1434605-1-seanjc@google.com> X-Mailer: git-send-email 2.47.0.rc1.288.g06298d1525-goog Message-ID: <20241010182427.1434605-15-seanjc@google.com> Subject: [PATCH v13 14/85] KVM: Return ERR_SIGPENDING from hva_to_pfn() if GUP returns -EGAIN From: Sean Christopherson To: 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 , Sean Christopherson Cc: 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, "=?UTF-8?q?Alex=20Benn=C3=A9e?=" , Yan Zhao , David Matlack , David Stevens , Andrew Jones Content-Type: text/plain; charset="UTF-8" Treat an -EAGAIN return from GUP the same as -EINTR and immediately report to the caller that a signal is pending. GUP only returns -EAGAIN if the _initial_ mmap_read_lock_killable() fails, which in turn onnly fails if a signal is pending Note, rwsem_down_read_slowpath() actually returns -EINTR, so GUP is really just making life harder than it needs to be. And the call to mmap_read_lock_killable() in the retry path returns its -errno verbatim, i.e. GUP (and thus KVM) is already handling locking failure this way, but only some of the time. Suggested-by: Paolo Bonzini Signed-off-by: Sean Christopherson --- virt/kvm/kvm_main.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 17acc75990a5..ebba5d22db2d 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -2946,7 +2946,7 @@ kvm_pfn_t hva_to_pfn(unsigned long addr, bool interruptible, bool *async, writable, &pfn); if (npages == 1) return pfn; - if (npages == -EINTR) + if (npages == -EINTR || npages == -EAGAIN) return KVM_PFN_ERR_SIGPENDING; mmap_read_lock(current->mm); -- 2.47.0.rc1.288.g06298d1525-goog