From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 523A423BCF0; Fri, 16 May 2025 12:15:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747397703; cv=none; b=hh0dgCgmr2rPvMmqV5cf1Xqdng9L/CrZ+MIHSCEvCw9BIaVPfidNlAQpOJ51U+8+wJuXXlcI2QZvYcxNxNEk2QBUIbd83NWkhBsMqaBR09qnHNPCygysIhrRcAlT1RdWNn6ZOXGoijlCjqnH3vLywM1sVcD6AXnfext65j1kleE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747397703; c=relaxed/simple; bh=HPNAKIztu+a2440f9Kb70RnSX4lQYGJ1p1Ou2Ufnvgo=; h=Date:Message-ID:From:To:Cc:Subject:In-Reply-To:References: MIME-Version:Content-Type; b=p0ZOqLqNeEdiz9ruZRFCf1Bs3rCxDPjB3ZnXNfXWHkztsf/fytvAgqvxEqHQo/YsHesOso3dvsqWV5gJz994upROBm2vegn5F/TKkANj089356GhtnvSt6G6nwVUp18b8P+NIjbyC2ncpApuf3L1oPs3wafVOTrWJp53KyEs8Bc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=gWOUtE7/; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="gWOUtE7/" Received: by smtp.kernel.org (Postfix) with ESMTPSA id BE260C4CEE4; Fri, 16 May 2025 12:15:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747397702; bh=HPNAKIztu+a2440f9Kb70RnSX4lQYGJ1p1Ou2Ufnvgo=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=gWOUtE7/2N7RRwb1BoUkR5QRUQnVyJ8poexLiswNHVp2UlMTD0n11qNHJxAJdNv4r pDPmNKe3PKmVwkjqcHdx7yr4rbpam16Qeh6bN8B16JkjbtVMlrX/GLbWvW8ntv7m6R +d8WXTdYeWJPJPQGYfnmhH2PEuL3kKN5u5IqLJTyIoJxa3N/L/0mu3yd3GUZH09C8Q vY9zejEHtPXox0hyVqnzoQTraUjzmEiR2nPN1PIojh13H1C9y+iqwlCPcDs1liao7R ATehvrsAk5sltNQRZKZo3RW7A5EKSJSbu2YWkdrnA1dIRFUeVjWfXduJb/wG6H9Bi+ kzcG58h5XJ/ZQ== Received: from sofa.misterjones.org ([185.219.108.64] helo=goblin-girl.misterjones.org) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1uFtxs-00FXzx-Mb; Fri, 16 May 2025 13:15:00 +0100 Date: Fri, 16 May 2025 13:15:00 +0100 Message-ID: <86bjrsg3az.wl-maz@kernel.org> From: Marc Zyngier To: Vincent Donnefort Cc: oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, qperret@google.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, kernel-team@android.com Subject: Re: [PATCH v4 01/10] KVM: arm64: Handle huge mappings for np-guest CMOs In-Reply-To: <20250509131706.2336138-2-vdonnefort@google.com> References: <20250509131706.2336138-1-vdonnefort@google.com> <20250509131706.2336138-2-vdonnefort@google.com> User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?UTF-8?B?R29qxY0=?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/30.1 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII X-SA-Exim-Connect-IP: 185.219.108.64 X-SA-Exim-Rcpt-To: vdonnefort@google.com, oliver.upton@linux.dev, joey.gouly@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, catalin.marinas@arm.com, will@kernel.org, qperret@google.com, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-kernel@vger.kernel.org, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false On Fri, 09 May 2025 14:16:57 +0100, Vincent Donnefort wrote: > > clean_dcache_guest_page() and invalidate_icache_guest_page() accept a > size as an argument. But they also rely on fixmap, which can only map a > single PAGE_SIZE page. > > With the upcoming stage-2 huge mappings for pKVM np-guests, those > callbacks will get size > PAGE_SIZE. Loop the CMOs on a PAGE_SIZE basis > until the whole range is done. > > Signed-off-by: Vincent Donnefort > > diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c > index 31173c694695..23544928a637 100644 > --- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c > +++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c > @@ -219,14 +219,28 @@ static void guest_s2_put_page(void *addr) > > static void clean_dcache_guest_page(void *va, size_t size) > { > - __clean_dcache_guest_page(hyp_fixmap_map(__hyp_pa(va)), size); > - hyp_fixmap_unmap(); > + WARN_ON(!PAGE_ALIGNED(size)); What if "va" isn't aligned? > + > + while (size) { > + __clean_dcache_guest_page(hyp_fixmap_map(__hyp_pa(va)), > + PAGE_SIZE); > + hyp_fixmap_unmap(); > + va += PAGE_SIZE; > + size -= PAGE_SIZE; > + } I know pKVM dies on WARN, but this code "looks" unsafe. Can you align va and size to be on page boundaries, so that we are 100% sure the loop terminates? > } > > static void invalidate_icache_guest_page(void *va, size_t size) > { > - __invalidate_icache_guest_page(hyp_fixmap_map(__hyp_pa(va)), size); > - hyp_fixmap_unmap(); > + WARN_ON(!PAGE_ALIGNED(size)); > + > + while (size) { > + __invalidate_icache_guest_page(hyp_fixmap_map(__hyp_pa(va)), > + PAGE_SIZE); > + hyp_fixmap_unmap(); > + va += PAGE_SIZE; > + size -= PAGE_SIZE; > + } Same here. Thanks, M. -- Without deviation from the norm, progress is not possible.