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Wed, 11 Sep 2024 17:10:04 +0100 Date: Wed, 11 Sep 2024 17:10:04 +0100 Message-ID: <86mske6ujn.wl-maz@kernel.org> From: Marc Zyngier To: Joey Gouly Cc: kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, James Morse , Suzuki K Poulose , Oliver Upton , Zenghui Yu , Alexandru Elisei , Mark Brown Subject: Re: [PATCH v3 18/24] KVM: arm64: Split S1 permission evaluation into direct and hierarchical parts In-Reply-To: <20240911155128.GA1087252@e124191.cambridge.arm.com> References: <20240911135151.401193-1-maz@kernel.org> <20240911135151.401193-19-maz@kernel.org> <20240911141513.GA1080224@e124191.cambridge.arm.com> <86o74u6vzu.wl-maz@kernel.org> <20240911155128.GA1087252@e124191.cambridge.arm.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/29.4 (aarch64-unknown-linux-gnu) MULE/6.0 (HANACHIRUSATO) 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: joey.gouly@arm.com, kvmarm@lists.linux.dev, linux-arm-kernel@lists.infradead.org, kvm@vger.kernel.org, james.morse@arm.com, suzuki.poulose@arm.com, oliver.upton@linux.dev, yuzenghui@huawei.com, alexandru.elisei@arm.com, broonie@kernel.org 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-20240911_091009_428079_7E83DA5B X-CRM114-Status: GOOD ( 20.26 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Wed, 11 Sep 2024 16:51:28 +0100, Joey Gouly wrote: > > On Wed, Sep 11, 2024 at 04:38:45PM +0100, Marc Zyngier wrote: > > On Wed, 11 Sep 2024 15:15:13 +0100, > > Joey Gouly wrote: > > > > > > On Wed, Sep 11, 2024 at 02:51:45PM +0100, Marc Zyngier wrote: > > > > [...] > > > > > > +static void compute_s1_hierarchical_permissions(struct kvm_vcpu *vcpu, > > > > + struct s1_walk_info *wi, > > > > + struct s1_walk_result *wr, > > > > + struct s1_perms *s1p) > > > > +{ > > > > > > How about: > > > > > > if (wi->hpd) > > > return; > > > > I was hoping not to add anything like this, because all the table bits > > are 0 (we simply don't collect them), and thus don't have any effect. > > I just thought it was more obvious that they wouldn't apply in this case, don't > feel super strongly about it. If you want it to be obvious, how about this instead? diff --git a/arch/arm64/kvm/at.c b/arch/arm64/kvm/at.c index 8a5e1c4682619..fb9de5fc2cc26 100644 --- a/arch/arm64/kvm/at.c +++ b/arch/arm64/kvm/at.c @@ -985,7 +985,8 @@ static void compute_s1_permissions(struct kvm_vcpu *vcpu, u32 op, else compute_s1_indirect_permissions(vcpu, wi, wr, s1p); - compute_s1_hierarchical_permissions(vcpu, wi, wr, s1p); + if (!wi->hpd) + compute_s1_hierarchical_permissions(vcpu, wi, wr, s1p); if (op == OP_AT_S1E1RP || op == OP_AT_S1E1WP) { bool pan; Thanks, M. -- Without deviation from the norm, progress is not possible.