From patchwork Thu Jun 5 15:37:51 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fuad Tabba X-Patchwork-Id: 894248 Received: from mail-wm1-f73.google.com (mail-wm1-f73.google.com [209.85.128.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0524219D092 for ; Thu, 5 Jun 2025 15:38:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749137904; cv=none; b=Rh9i3JygqMAqVopVJG2x9UWEyR9BWK2UDnrCOpe2409S4RuJzNyyzoSAuG3eUs7KwP3ibUBD/aSg9v/IU0X8FtMSCEXJNljTSmfl0BHqzi1TsvVh+lPcNMT1KymZcAIHGG9KOTvXr5039q3dYG8oeyio8kbh5s9CZcm2PWlYCEo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749137904; c=relaxed/simple; bh=/gDlC+c+mYbhEIjFER9Aypoi49xuhmQpWh2Jln/swxw=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=IibwCaRc4ogmlu/TkMwYrJ6Ce/SylsuIE7q60NXG3V+YkzcY1uf5aiHu5cZh42L/KY+86yR2MvbZMmqfnSDpYV09Hec3DtNb3y/AAULeHv6HXSq5fVPvVZZ+6MCKU6GXHW1nL35Zhn8jD90EuNKTaa/BQ1dstu+ka/F9lQYkbwE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--tabba.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=bxP8yivv; arc=none smtp.client-ip=209.85.128.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--tabba.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="bxP8yivv" Received: by mail-wm1-f73.google.com with SMTP id 5b1f17b1804b1-450cf229025so3238425e9.1 for ; Thu, 05 Jun 2025 08:38:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1749137901; x=1749742701; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=sMdvYQ/d0VW8VpJk25WKourz4e44AIQm8pQAcHG28VM=; b=bxP8yivvo5aAQF7BLgoYQoFDCm8IrD4EA3rkr7T6QLnUOQxeeqRlhANIb5dz/W/OAH SyVNZSpFhMLMBR1rFsxeBC3amA1WQNgd9SGezy/754EgAP1X+xs44WgUrlL8xk40sg72 shEmOW+XVPZ97s4VSskX3vi3goKKBo9cPHhhJexahlp2RZtIWqZDJl0URjI896MMIUD8 kEKNxvugxgUH1e+MlT6fdMfGpJiDgOrdA8khmIX7XglRRO/0nneENXRYnyvZc3eTGipe m3ioABh/sYOD5Dn3W1oZWXmwy5hkqGAjRXWiwPB9CQa4yYYBCvHU+6YeRtoZztK8gY9x MsvQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1749137901; x=1749742701; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=sMdvYQ/d0VW8VpJk25WKourz4e44AIQm8pQAcHG28VM=; b=t6Pck8BBaQ8Vrxq/mA3Ne1HJI9oOGDh10ZUMp3efAm+k42TTG06udH6ytVASOWJDRA 12hgjeCwm5RWttF4hv7YR2ZFzedLq4D4js60KV5JdRdcFsq1yyyaXOifgvDQ72BBC9Wb ActFkRiyMNGnn5X96OO39Z4984lpOh9/D1gU8LGiAuduyJiIVkO5i/LpbtRnoZPqDfCe WZZNl03XH610HAQEzOyEoqVQP8/Xxr4DPi1MhTnuxbSPv0kouegNDtZ34d+VcP4es64g fAAt6/Isjk9vRMGNCB12T2NtopZ7y8Wku6wZxiHnfOVIYaFfXAGNM3fq3qldcdABfm/R GZCg== X-Forwarded-Encrypted: i=1; AJvYcCWZM0a+W7vrNQ3aSWDTxthCneyJE2RUSgSBrISjKfo/1Ap4Xtljq+es4sCBv4CuCaKbYDyjVmwwK7IqqKsS@vger.kernel.org X-Gm-Message-State: AOJu0Yx7H5rnI/hIVltDqbdh4a2t/O8bQR+OzuCdhDX6xZ9h2WpZnSXO IiaJd3SDW9gWawXFPAVyc8iNHa2eE+dMgldFGlVjcn0enQw0ujNp+/V17P+SZovXIkK9dfHRx8a +rA== X-Google-Smtp-Source: AGHT+IF6u3Z6Htlnfn5ZxQZU8datzZcfLbCYrTGAifog68TQ1MWi4ePY32WlwAmGrzeUYho49K/iYdDukw== X-Received: from wmbjh14.prod.google.com ([2002:a05:600c:a08e:b0:442:f9ef:e460]) (user=tabba job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:870c:b0:43c:ee3f:2c3 with SMTP id 5b1f17b1804b1-451f0a636ebmr71631385e9.7.1749137901405; Thu, 05 Jun 2025 08:38:21 -0700 (PDT) Date: Thu, 5 Jun 2025 16:37:51 +0100 In-Reply-To: <20250605153800.557144-1-tabba@google.com> Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250605153800.557144-1-tabba@google.com> X-Mailer: git-send-email 2.49.0.1266.g31b7d2e469-goog Message-ID: <20250605153800.557144-10-tabba@google.com> Subject: [PATCH v11 09/18] KVM: guest_memfd: Track shared memory support in memslot From: Fuad Tabba To: kvm@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-mm@kvack.org, kvmarm@lists.linux.dev Cc: pbonzini@redhat.com, chenhuacai@kernel.org, mpe@ellerman.id.au, anup@brainfault.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, seanjc@google.com, viro@zeniv.linux.org.uk, brauner@kernel.org, willy@infradead.org, akpm@linux-foundation.org, xiaoyao.li@intel.com, yilun.xu@intel.com, chao.p.peng@linux.intel.com, jarkko@kernel.org, amoorthy@google.com, dmatlack@google.com, isaku.yamahata@intel.com, mic@digikod.net, vbabka@suse.cz, vannapurve@google.com, ackerleytng@google.com, mail@maciej.szmigiero.name, david@redhat.com, michael.roth@amd.com, wei.w.wang@intel.com, liam.merwick@oracle.com, isaku.yamahata@gmail.com, kirill.shutemov@linux.intel.com, suzuki.poulose@arm.com, steven.price@arm.com, quic_eberman@quicinc.com, quic_mnalajal@quicinc.com, quic_tsoni@quicinc.com, quic_svaddagi@quicinc.com, quic_cvanscha@quicinc.com, quic_pderrin@quicinc.com, quic_pheragu@quicinc.com, catalin.marinas@arm.com, james.morse@arm.com, yuzenghui@huawei.com, oliver.upton@linux.dev, maz@kernel.org, will@kernel.org, qperret@google.com, keirf@google.com, roypat@amazon.co.uk, shuah@kernel.org, hch@infradead.org, jgg@nvidia.com, rientjes@google.com, jhubbard@nvidia.com, fvdl@google.com, hughd@google.com, jthoughton@google.com, peterx@redhat.com, pankaj.gupta@amd.com, ira.weiny@intel.com, tabba@google.com Add a new internal flag in the top half of memslot->flags to track when a guest_memfd-backed slot supports shared memory, which is reserved for internal use in KVM. This avoids repeatedly checking the underlying guest_memfd file for shared memory support, which requires taking a reference on the file. Suggested-by: David Hildenbrand Signed-off-by: Fuad Tabba --- include/linux/kvm_host.h | 11 ++++++++++- virt/kvm/guest_memfd.c | 2 ++ 2 files changed, 12 insertions(+), 1 deletion(-) diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h index 640ce714cfb2..6326d1ad8225 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -54,7 +54,8 @@ * used in kvm, other bits are visible for userspace which are defined in * include/uapi/linux/kvm.h. */ -#define KVM_MEMSLOT_INVALID (1UL << 16) +#define KVM_MEMSLOT_INVALID (1UL << 16) +#define KVM_MEMSLOT_SUPPORTS_GMEM_SHARED (1UL << 17) /* * Bit 63 of the memslot generation number is an "update in-progress flag", @@ -2502,6 +2503,14 @@ static inline void kvm_prepare_memory_fault_exit(struct kvm_vcpu *vcpu, vcpu->run->memory_fault.flags |= KVM_MEMORY_EXIT_FLAG_PRIVATE; } +static inline bool kvm_gmem_memslot_supports_shared(const struct kvm_memory_slot *slot) +{ + if (!IS_ENABLED(CONFIG_KVM_GMEM_SHARED_MEM)) + return false; + + return slot->flags & KVM_MEMSLOT_SUPPORTS_GMEM_SHARED; +} + #ifdef CONFIG_KVM_GENERIC_MEMORY_ATTRIBUTES static inline unsigned long kvm_get_memory_attributes(struct kvm *kvm, gfn_t gfn) { diff --git a/virt/kvm/guest_memfd.c b/virt/kvm/guest_memfd.c index 7a158789d1df..e0fa49699e05 100644 --- a/virt/kvm/guest_memfd.c +++ b/virt/kvm/guest_memfd.c @@ -595,6 +595,8 @@ int kvm_gmem_bind(struct kvm *kvm, struct kvm_memory_slot *slot, */ WRITE_ONCE(slot->gmem.file, file); slot->gmem.pgoff = start; + if (kvm_gmem_supports_shared(inode)) + slot->flags |= KVM_MEMSLOT_SUPPORTS_GMEM_SHARED; xa_store_range(&gmem->bindings, start, end - 1, slot, GFP_KERNEL); filemap_invalidate_unlock(inode->i_mapping);