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Shutemov" , "Kirill A. Shutemov" , Dave Hansen , Andy Lutomirski , "Peter Zijlstra" , , Kostya Serebryany , Andrey Ryabinin , Andrey Konovalov , Alexander Potapenko , Taras Madan , Dmitry Vyukov , "H . J . Lu" , Andi Kleen , Rick Edgecombe , , , Ashok Raj , jacob.jun.pan@intel.com Subject: Re: [PATCHv8 00/11] Linear Address Masking enabling Message-ID: <20220912133935.3bb3e247@jacob-builder> In-Reply-To: References: <20220830010104.1282-1-kirill.shutemov@linux.intel.com> <20220904003952.fheisiloilxh3mpo@box.shutemov.name> Organization: OTC X-Mailer: Claws Mail 3.17.5 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1663014974; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=oBl2sKcRqcTqT8nHrZiNuE5eI4us2BpLhXrEMSMu3CA=; b=NNRjQUpUaKVTS/4msvX0T//UsDUndvJ6iJCeYilqrscTj+rTUF5gTJ4+d3h4NNhbTHVPc1 IxGVZO9xjnSWq+oMY3wnnzM85X2rYnw5dEdB3Hg+Bv3IrpBOgRNaooilePxvLteNQDXh0+ iA1oyNc8f6acLtZwOt9ry0VbOrCD4/s= ARC-Authentication-Results: i=1; imf23.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=RO+iSqqV; spf=pass (imf23.hostedemail.com: domain of jacob.jun.pan@intel.com designates 134.134.136.24 as permitted sender) smtp.mailfrom=jacob.jun.pan@intel.com; dmarc=pass (policy=none) header.from=intel.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1663014974; a=rsa-sha256; cv=none; b=hyX9QjOvsSjRm7oiSXredi58tblc+e09v6b16QvRV2PLZ2HSS7XDYRPx335tQZhbB6xhNB 5MGBO7SCCH68j6FkbbVrBINsiWSkuUNFZ/jHjCzWlOFY1s7OMLxZqq7UoXw9rcDrn6T/AJ MbkYUDceR2wWcCkjEYRl/iyfInPCEuA= X-Stat-Signature: jugz3z3zzis3gajga15fxspawmsa7frh X-Rspamd-Queue-Id: 285371400A4 Authentication-Results: imf23.hostedemail.com; dkim=none ("invalid DKIM record") header.d=intel.com header.s=Intel header.b=RO+iSqqV; spf=pass (imf23.hostedemail.com: domain of jacob.jun.pan@intel.com designates 134.134.136.24 as permitted sender) smtp.mailfrom=jacob.jun.pan@intel.com; dmarc=pass (policy=none) header.from=intel.com X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1663014973-890430 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi Ashok, On Fri, 9 Sep 2022 16:08:02 +0000, Ashok Raj wrote: > > diff --git a/arch/x86/include/uapi/asm/prctl.h > > b/arch/x86/include/uapi/asm/prctl.h index a31e27b95b19..e5c04ced36c9 > > 100644 --- a/arch/x86/include/uapi/asm/prctl.h > > +++ b/arch/x86/include/uapi/asm/prctl.h > > @@ -23,5 +23,6 @@ > > #define ARCH_GET_UNTAG_MASK 0x4001 > > #define ARCH_ENABLE_TAGGED_ADDR 0x4002 > > #define ARCH_GET_MAX_TAG_BITS 0x4003 > > +#define ARCH_ENABLE_TAGGED_ADDR_FORCED 0x4004 > > > > #endif /* _ASM_X86_PRCTL_H */ > > diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c > > index 337f80a0862f..7d89a2fd1a55 100644 > > --- a/arch/x86/kernel/process_64.c > > +++ b/arch/x86/kernel/process_64.c > > @@ -774,7 +774,8 @@ static bool lam_u48_allowed(void) > > #define LAM_U48_BITS 15 > > #define LAM_U57_BITS 6 > > > > -static int prctl_enable_tagged_addr(struct mm_struct *mm, unsigned > > long nr_bits) +static int prctl_enable_tagged_addr(struct mm_struct > > *mm, unsigned long nr_bits, > > + bool forced) > > { > > int ret = 0; > > > > @@ -793,6 +794,11 @@ static int prctl_enable_tagged_addr(struct > > mm_struct *mm, unsigned long nr_bits) goto out; > > } > > > > + if (pasid_valid(mm->pasid) && !forced) { I don't think this works since we have lazy pasid free. for example, after all the devices did sva_unbind, mm->pasid we'll remain valid until mmdrop(). LAM should be supported in this case. Perhaps, we could introduce another prctl flag for SVA, PR_GET_SVA? Both iommu driver and LAM can set/query the flag. LAM applications may not be the only ones want to know if share virtual addressing is on. > > + ret = -EBUSY; > > + goto out; > > + } > > + Thanks, Jacob