From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9401B6079D45 for ; Mon, 19 Oct 2026 15:00:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=AozimXbZ; dkim=pass (2048-bit key, unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20251104 header.b=sJYCDYPY DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:Cc:To:From: Subject:Message-ID:Mime-Version:Date:Reply-To:Content-Transfer-Encoding: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:In-Reply-To:References:List-Owner; bh=Meq30BGUrGHp6xcOF0w5JprFYd5g2Y2UtUcpUpaVjGQ=; b=AozimXbZxDc0xvd5n7/E7KkrZa jVsfuo+CCft27MtPJsGeI8+BrcKHLUZ0NdQudc4RnEvCp4cTslfy1R3Gkdxu5aX4MVgHNiMD1/uE1 H3LVelUywooT2yAab0LC+cSU5jBokeMo//uDsVuZt5a0+l+htr2jdxdxuCJKBeQ5BJSy43gTBWivv Bn85xmc4/skl4p8U7YTfzlGmt4J4SphqXPAEUnp7qr1sk5kfFhsWCDSuYIFjJbgGdsRxsBChL1Oll jm6guWZH18ZZ/yQhK1Cog5fTD0l9vtX+g0mn8O213R6gYwZMEZKXAHbznLFZG7W4Cu1cfym4iVEbi 3elnO1/w==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xIoqF-00000007nQH-3x7D; Mon, 19 Oct 2026 14:59:59 +0000 Received: from mail-wr1-x446.google.com ([2a00:1450:4864:20::446]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xIoqD-00000007nPi-2qOs for linux-arm-kernel@lists.infradead.org; Mon, 19 Oct 2026 14:59:58 +0000 Received: by mail-wr1-x446.google.com with SMTP id ffacd0b85a97d-48af5a07314so1359968f8f.2 for ; Mon, 19 Oct 2026 07:59:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1792421995; x=1793026795; darn=lists.infradead.org; h=content-type:cc:to:from:subject:message-id:mime-version:date:from :to:cc:subject:date:message-id:reply-to:content-type; bh=Meq30BGUrGHp6xcOF0w5JprFYd5g2Y2UtUcpUpaVjGQ=; b=sJYCDYPYguJm89clBUcZgSJQogvjD/gub6kmF1/zNAs1t2HcXpf7QSoLNlBwAK8/JF v4anXqbe+MkCK8yRhSyTNt4GOJ6gQRVKxo3N1VeI6lhEvqEepG+7f2o+G6OsCT4K+nFc iqIxU1s58Sbfn/0kB2oDORw4JIk5A4fYNioep0NG3/z2uCWWkWikk1R4sh5qPzCuPo3b FbR6yF6KPplXeG2s8et1ekAjOxoEBQ4xynmTU3Xz1150iJdmkbbeSNghHqKvThT7bTXP rrBpzcKTiX2G+THk4avbvNjdh/1qRFo81Q03XHQclIBUuOPvVwFUbBToDZ6Nwt7rodLi oZPA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1792421995; x=1793026795; h=content-type:cc:to:from:subject:message-id:mime-version:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=Meq30BGUrGHp6xcOF0w5JprFYd5g2Y2UtUcpUpaVjGQ=; b=JOR+HQhCPBSYBeEoCm38njDWB6JC5OW9qj3DB59496iGKi20pHBkpdzwUcEoS5jSIr /ajMZzZa5x3Jy1x4ak2Qki/+hbGXUEwzK0O+rZd2bk8A/zjH7ghp1ANshWFjvC9Ka1Ge x31OazuxcigrUeMN1uEpOvmrVzPf1gd1O2WN6hQmdsSbM4xoA/CMnMRZ4mYTj8IEF4Cu GUdMu2yxcb5YlX6k47vwZ/B/l0nTF6cKQtIHq/dEuBHmvSNJgveaw6Ri54LBx3hG3Fk3 mrBNhyDkrPHJF6rXA2K3c7UeUkfdQVF4f4DMChc2fKBux2UEfB6N+XxXRF+hHSsmbcv1 kMjg== X-Forwarded-Encrypted: i=1; AKwUvBwyTQuDOHYhrUHP/bd3Sn6cwksxKDQeiOg6n6gJ2/XX1/lVlrRLjGqBzYkmQLcwrvv/oPYEt2jUCODNbUfKzsQ7@lists.infradead.org X-Gm-Message-State: AFq9FYJa5sMflirMpkyPMgPWmAdff17zZkxxO9zUqlGbDwfg55m+2772 gKiIcWB/WR/OY1j7tX8rUU1HNKT6FlpFOUcurwoGvWMGwzaxkyVG3R82/DwsSqqF0Y9nPGAQYNE kzg7/SQkgkRpO3yknjIS9kQ== X-Received: from wrus7.prod.google.com ([2002:a5d:6a87:0:b0:48e:1449:1f6c]) (user=vdonnefort job=prod-delivery.src-stubby-dispatcher) by 2002:a5d:60cc:0:b0:48d:f14a:9177 with SMTP id ffacd0b85a97d-48e07fb9180mr11409788f8f.56.1792421995213; Mon, 19 Oct 2026 07:59:55 -0700 (PDT) Date: Mon, 19 Oct 2026 15:59:49 +0100 X-Archived-By: Mime-Version: 1.0 X-Mailer: git-send-email 2.56.0.176.g3575e65682-goog Message-ID: <20261019145949.1922019-1-vdonnefort@google.com> Subject: [PATCH kvmtool] arm64: THPs for systems with pages bigger than 4K From: Vincent Donnefort To: will@kernel.org, julien.thierry.kdev@gmail.com Cc: kvm@vger.kernel.org, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, maz@kernel.org, oliver.upton@linux.dev, suzuki.poulose@arm.com, alexandru.elisei@arm.com, andre.przywara@arm.com, Vincent Donnefort Content-Type: text/plain; charset="UTF-8" X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261019_075957_765564_CABF7757 X-CRM114-Status: GOOD ( 13.50 ) X-Spam-Score: -9.5 (---------) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" X-Spam-Status: No, score=-26.7 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIMWL_WL_MED,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,RCVD_IN_DNSWL_BLOCKED,RCVD_IN_ZEN_BLOCKED_OPENDNS, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 The THP support imposes an alignment of the memslot userspace address to the size of a THP (PMD_SIZE). To do so, kvmtool overallocates the RAM size and aligns it. However it assumes PMD_SIZE is 2MiB, which is only true on 4KiB page systems. Use a huge-page size, based on the system page size. This value can be massive for a 64KiB page system, so skip the alignment if we couldn't even install one THP. Signed-off-by: Vincent Donnefort diff --git a/arm64/kvm.c b/arm64/kvm.c index 36b3284e4a92..2c01dc32fa9a 100644 --- a/arm64/kvm.c +++ b/arm64/kvm.c @@ -18,6 +18,8 @@ #include +#define HUGEPAGE_SIZE (PAGE_SIZE * (PAGE_SIZE / 8UL)) + static struct arm64_image_header *kernel_header; struct kvm_ext kvm_req_ext[] = { @@ -35,20 +37,23 @@ bool kvm__arch_cpu_supports_vm(void) void kvm__init_ram(struct kvm *kvm) { - u64 phys_start, phys_size; + u64 phys_start, phys_size, ram_alloc_align = SZ_64K; void *host_mem; int err; /* - * Allocate guest memory. We must align our buffer to 64K to - * correlate with the maximum guest page size for virtio-mmio. - * If using THP, then our minimal alignment becomes 2M. - * 2M trumps 64K, so let's go with that. + * Allocate guest memory. We must align our buffer to 64K to correlate + * with the maximum guest page size for virtio-mmio. If using THP, then + * our minimal alignment trumps 64K, so let's go with that. */ kvm->ram_size = kvm->cfg.ram_size; kvm->arch.ram_alloc_size = kvm->ram_size; - if (!kvm->cfg.hugetlbfs_path) - kvm->arch.ram_alloc_size += SZ_2M; + if (!kvm->cfg.hugetlbfs_path) { + if (kvm->ram_size >= HUGEPAGE_SIZE) + ram_alloc_align = HUGEPAGE_SIZE; + + kvm->arch.ram_alloc_size += ram_alloc_align; + } if (kvm->cfg.arch.guest_memfd) kvm->arch.ram_alloc_start = mmap_guest_memfd(kvm, @@ -63,7 +68,7 @@ void kvm__init_ram(struct kvm *kvm) kvm->arch.ram_alloc_size, errno); kvm->ram_start = (void *)ALIGN((unsigned long)kvm->arch.ram_alloc_start, - SZ_2M); + ram_alloc_align); if (!kvm->cfg.arch.guest_memfd) { madvise(kvm->arch.ram_alloc_start, kvm->arch.ram_alloc_size, base-commit: f67bc0bdae9433a9cfd05e65ea2c1bb6102566d9 -- 2.56.0.176.g3575e65682-goog