From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D4551C4361B for ; Tue, 15 Dec 2020 13:20:11 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9C02322225 for ; Tue, 15 Dec 2020 13:20:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9C02322225 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; 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Tue, 15 Dec 2020 13:18:43 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1kpADu-0001Fv-99 for linux-arm-kernel@lists.infradead.org; Tue, 15 Dec 2020 13:18:41 +0000 Received: from disco-boy.misterjones.org (disco-boy.misterjones.org [51.254.78.96]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7D3D722225; Tue, 15 Dec 2020 13:18:37 +0000 (UTC) Received: from disco-boy.misterjones.org ([51.254.78.96] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94) (envelope-from ) id 1kpADr-001URY-9d; Tue, 15 Dec 2020 13:18:35 +0000 MIME-Version: 1.0 Date: Tue, 15 Dec 2020 13:18:35 +0000 From: Marc Zyngier To: "wangyanan (Y)" Subject: Re: [RFC PATCH] KVM: arm64: Add prejudgement for relaxing permissions only case in stage2 translation fault handler In-Reply-To: <2ab9323a-40a1-d223-f692-0a19207e16a9@huawei.com> References: <20201211080115.21460-1-wangyanan55@huawei.com> <20201211080115.21460-2-wangyanan55@huawei.com> <8d006755e5afce7e49b03993316c4fcc@kernel.org> <20201211100026.GA11352@willie-the-truck> <2ab9323a-40a1-d223-f692-0a19207e16a9@huawei.com> User-Agent: Roundcube Webmail/1.4.9 Message-ID: <9a3bd48c4e69946bc4ade274ce2cc318@kernel.org> X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: wangyanan55@huawei.com, will@kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, gshan@redhat.com, qperret@google.com, wanghaibin.wang@huawei.com, yezengruan@huawei.com, zhukeqian1@huawei.com, yuzenghui@huawei.com, jiangkunkun@huawei.com, wangjingyi11@huawei.com, lushenming@huawei.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201215_081838_442425_9F1685E2 X-CRM114-Status: GOOD ( 18.86 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: jiangkunkun@huawei.com, Gavin Shan , lushenming@huawei.com, Suzuki K Poulose , Catalin Marinas , zhukeqian1@huawei.com, Quentin Perret , wangjingyi11@huawei.com, linux-kernel@vger.kernel.org, yezengruan@huawei.com, James Morse , linux-arm-kernel@lists.infradead.org, yuzenghui@huawei.com, wanghaibin.wang@huawei.com, Will Deacon , Julien Thierry Content-Transfer-Encoding: base64 Content-Type: text/plain; charset="utf-8"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org SGkgWWFuYW4sCgpPbiAyMDIwLTEyLTE0IDA3OjIwLCB3YW5neWFuYW4gKFkpIHdyb3RlOgoKPiBk aWZmIC0tZ2l0IGEvYXJjaC9hcm02NC9rdm0vaHlwL3BndGFibGUuYyAKPiBiL2FyY2gvYXJtNjQv a3ZtL2h5cC9wZ3RhYmxlLmMKPiBpbmRleCBhNzRhNjIyODMwMTIuLmUzYzYxMzM1NjdjNCAxMDA2 NDQKPiAtLS0gYS9hcmNoL2FybTY0L2t2bS9oeXAvcGd0YWJsZS5jCj4gKysrIGIvYXJjaC9hcm02 NC9rdm0vaHlwL3BndGFibGUuYwo+IEBAIC00NSw2ICs0NSwxMCBAQAo+IAo+IMKgI2RlZmluZSBL Vk1fUFRFX0xFQUZfQVRUUl9ISV9TMl9YTsKgwqDCoMKgIEJJVCg1NCkKPiAKPiArI2RlZmluZSBL Vk1fUFRFX0xFQUZfQVRUUl9TMl9QRVJNUyAoS1ZNX1BURV9MRUFGX0FUVFJfTE9fUzJfUzJBUF9S IHwgXAo+ICsgwqAgwqAgwqDCoCBLVk1fUFRFX0xFQUZfQVRUUl9MT19TMl9TMkFQX1cgfCBcCj4g KyBLVk1fUFRFX0xFQUZfQVRUUl9ISV9TMl9YTikKPiArCj4gwqBzdHJ1Y3Qga3ZtX3BndGFibGVf d2Fsa19kYXRhIHsKPiDCoMKgwqDCoMKgwqDCoCBzdHJ1Y3Qga3ZtX3BndGFibGXCoMKgwqDCoMKg wqDCoMKgwqDCoMKgwqDCoMKgwqDCoMKgwqAgKnBndDsKPiDCoMKgwqDCoMKgwqDCoCBzdHJ1Y3Qg a3ZtX3BndGFibGVfd2Fsa2VywqDCoMKgwqDCoMKgICp3YWxrZXI7Cj4gQEAgLTQ3Myw4ICs0Nzcs MTMgQEAgc3RhdGljIGJvb2wgc3RhZ2UyX21hcF93YWxrZXJfdHJ5X2xlYWYodTY0IGFkZHIsCj4g dTY0IGVuZCwgdTMyIGxldmVsLAo+IAo+IMKgwqDCoMKgwqDCoMKgIG5ldyA9IGt2bV9pbml0X3Zh bGlkX2xlYWZfcHRlKHBoeXMsIGRhdGEtPmF0dHIsIGxldmVsKTsKPiDCoMKgwqDCoMKgwqDCoCBp ZiAoa3ZtX3B0ZV92YWxpZChvbGQpKSB7Cj4gLcKgwqDCoMKgwqDCoMKgwqDCoMKgwqDCoMKgwqAg LyogVG9sZXJhdGUgS1ZNIHJlY3JlYXRpbmcgdGhlIGV4YWN0IHNhbWUgbWFwcGluZy4gKi8KPiAt wqDCoMKgwqDCoMKgwqDCoMKgwqDCoMKgwqDCoCBpZiAob2xkID09IG5ldykKPiArwqDCoMKgwqDC oMKgwqDCoMKgwqDCoMKgwqDCoCAvKgo+ICvCoMKgwqDCoMKgwqDCoMKgwqDCoMKgwqDCoMKgwqAg KiBTa2lwIHVwZGF0aW5nIHRoZSBQVEUgd2l0aCBicmVhay1iZWZvcmUtbWFrZSBpZiB3ZSAKPiBh cmUgdHJ5aW5nCj4gK8KgwqDCoMKgwqDCoMKgwqDCoMKgwqDCoMKgwqDCoCAqIHRvIHJlY3JlYXRl IHRoZSBleGFjdCBzYW1lIG1hcHBpbmcgb3Igb25seSBjaGFuZ2UgCj4gdGhlIGFjY2Vzcwo+ICvC oMKgwqDCoMKgwqDCoMKgwqDCoMKgwqDCoMKgwqAgKiBwZXJtaXNzaW9ucy4gQWN0dWFsbHksIGNo YW5nZSBvZiBwZXJtaXNzaW9ucyB3aWxsIGJlIAo+IGhhbmRsZWQKPiArwqDCoMKgwqDCoMKgwqDC oMKgwqDCoMKgwqDCoMKgICogdGhyb3VnaCB0aGUgcmVsYXhfcGVybXMgcGF0aCBuZXh0IHRpbWUg aWYgbmVjZXNzYXJ5Lgo+ICvCoMKgwqDCoMKgwqDCoMKgwqDCoMKgwqDCoMKgwqAgKi8KPiArwqDC oMKgwqDCoMKgwqDCoMKgwqDCoMKgwqDCoCBpZiAoISgob2xkIF4gbmV3KSAmICh+S1ZNX1BURV9M RUFGX0FUVFJfUzJfUEVSTVMpKSkKPiDCoMKgwqDCoMKgwqDCoMKgwqDCoMKgwqDCoMKgwqDCoMKg wqDCoMKgwqDCoMKgIGdvdG8gb3V0Owo+IAo+IMKgwqDCoMKgwqDCoMKgwqDCoMKgwqDCoMKgwqDC oCAvKiBUaGVyZSdzIGFuIGV4aXN0aW5nIGRpZmZlcmVudCB2YWxpZCBsZWFmIGVudHJ5LCBzbyAK PiBwZXJmb3JtCgpJIHRoaW5rIHRoZXJlIGlzIGEgYml0IG1vcmUgd29yayB0byBkbyBvbiB0aGlz LgoKT25lIG9idmlvdXMgaXNzdWUgaXMgdGhhdCB3ZSBjdXJyZW50bHkgZmxhZyBhIHBhZ2UgYXMg ZGlydHkgYmVmb3JlIApoYW5kbGluZwp0aGUgZmF1bHQuIFdpdGggYW4gZWFybHkgZXhpdCwgd2Ug ZW5kLXVwIGhhdmluZyBzcHVyaW91cyBkaXJ0eSBwYWdlcy4KCkl0J3Mgbm90IGEgYmlnIGRlYWws IGJ1dCBJJ2QgcmF0aGVyIG1hcmsgdGhlIHBhZ2UgZGlydHkgYWZ0ZXIgdGhlIAptYXBwaW5nCm9y IHRoZSBwZXJtaXNzaW9uIHVwZGF0ZSBoYXZpbmcgYmVlbiBzdWNjZXNzZnVsIChhdCB0aGUgbW9t ZW50LCBpdCAKY2Fubm90CmZhaWxzKS4KClRoYW5rcywKCiAgICAgICAgIE0uCi0tIApKYXp6IGlz IG5vdCBkZWFkLiBJdCBqdXN0IHNtZWxscyBmdW5ueS4uLgoKX19fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX18KbGludXgtYXJtLWtlcm5lbCBtYWlsaW5nIGxpc3QK bGludXgtYXJtLWtlcm5lbEBsaXN0cy5pbmZyYWRlYWQub3JnCmh0dHA6Ly9saXN0cy5pbmZyYWRl YWQub3JnL21haWxtYW4vbGlzdGluZm8vbGludXgtYXJtLWtlcm5lbAo= From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=BAYES_00,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5C5F7C4361B for ; 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Tue, 15 Dec 2020 13:18:35 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Date: Tue, 15 Dec 2020 13:18:35 +0000 From: Marc Zyngier To: "wangyanan (Y)" Cc: Will Deacon , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Catalin Marinas , James Morse , Julien Thierry , Suzuki K Poulose , Gavin Shan , Quentin Perret , wanghaibin.wang@huawei.com, yezengruan@huawei.com, zhukeqian1@huawei.com, yuzenghui@huawei.com, jiangkunkun@huawei.com, wangjingyi11@huawei.com, lushenming@huawei.com Subject: Re: [RFC PATCH] KVM: arm64: Add prejudgement for relaxing permissions only case in stage2 translation fault handler In-Reply-To: <2ab9323a-40a1-d223-f692-0a19207e16a9@huawei.com> References: <20201211080115.21460-1-wangyanan55@huawei.com> <20201211080115.21460-2-wangyanan55@huawei.com> <8d006755e5afce7e49b03993316c4fcc@kernel.org> <20201211100026.GA11352@willie-the-truck> <2ab9323a-40a1-d223-f692-0a19207e16a9@huawei.com> User-Agent: Roundcube Webmail/1.4.9 Message-ID: <9a3bd48c4e69946bc4ade274ce2cc318@kernel.org> X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: wangyanan55@huawei.com, will@kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, catalin.marinas@arm.com, james.morse@arm.com, julien.thierry.kdev@gmail.com, suzuki.poulose@arm.com, gshan@redhat.com, qperret@google.com, wanghaibin.wang@huawei.com, yezengruan@huawei.com, zhukeqian1@huawei.com, yuzenghui@huawei.com, jiangkunkun@huawei.com, wangjingyi11@huawei.com, lushenming@huawei.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Yanan, On 2020-12-14 07:20, wangyanan (Y) wrote: > diff --git a/arch/arm64/kvm/hyp/pgtable.c > b/arch/arm64/kvm/hyp/pgtable.c > index a74a62283012..e3c6133567c4 100644 > --- a/arch/arm64/kvm/hyp/pgtable.c > +++ b/arch/arm64/kvm/hyp/pgtable.c > @@ -45,6 +45,10 @@ > >  #define KVM_PTE_LEAF_ATTR_HI_S2_XN     BIT(54) > > +#define KVM_PTE_LEAF_ATTR_S2_PERMS (KVM_PTE_LEAF_ATTR_LO_S2_S2AP_R | \ > +        KVM_PTE_LEAF_ATTR_LO_S2_S2AP_W | \ > + KVM_PTE_LEAF_ATTR_HI_S2_XN) > + >  struct kvm_pgtable_walk_data { >         struct kvm_pgtable                   *pgt; >         struct kvm_pgtable_walker       *walker; > @@ -473,8 +477,13 @@ static bool stage2_map_walker_try_leaf(u64 addr, > u64 end, u32 level, > >         new = kvm_init_valid_leaf_pte(phys, data->attr, level); >         if (kvm_pte_valid(old)) { > -               /* Tolerate KVM recreating the exact same mapping. */ > -               if (old == new) > +               /* > +                * Skip updating the PTE with break-before-make if we > are trying > +                * to recreate the exact same mapping or only change > the access > +                * permissions. Actually, change of permissions will be > handled > +                * through the relax_perms path next time if necessary. > +                */ > +               if (!((old ^ new) & (~KVM_PTE_LEAF_ATTR_S2_PERMS))) >                         goto out; > >                 /* There's an existing different valid leaf entry, so > perform I think there is a bit more work to do on this. One obvious issue is that we currently flag a page as dirty before handling the fault. With an early exit, we end-up having spurious dirty pages. It's not a big deal, but I'd rather mark the page dirty after the mapping or the permission update having been successful (at the moment, it cannot fails). Thanks, M. -- Jazz is not dead. It just smells funny...