Re: [PATCH v6 03/12] KVM: arm64: Move early handlers to per-EC handlers

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From: Marc Zyngier <maz@kernel.org>
To: Will Deacon <will@kernel.org>
Cc: Fuad Tabba <tabba@google.com>,
	kvmarm@lists.cs.columbia.edu, james.morse@arm.com,
	alexandru.elisei@arm.com, suzuki.poulose@arm.com,
	mark.rutland@arm.com, christoffer.dall@arm.com,
	pbonzini@redhat.com, drjones@redhat.com, oupton@google.com,
	qperret@google.com, kvm@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, kernel-team@android.com
Subject: Re: [PATCH v6 03/12] KVM: arm64: Move early handlers to per-EC handlers
Date: Thu, 30 Sep 2021 17:02:55 +0100	[thread overview]
Message-ID: <2b007cfc37203c84237d4a523cb0cadb@kernel.org> (raw)
In-Reply-To: <20210930133444.GC23809@willie-the-truck>

On 2021-09-30 14:35, Will Deacon wrote:
> On Wed, Sep 22, 2021 at 01:46:55PM +0100, Fuad Tabba wrote:
>> From: Marc Zyngier <maz@kernel.org>

>> +static bool kvm_hyp_handle_cp15(struct kvm_vcpu *vcpu, u64 
>> *exit_code)
>> +{
>> +	if (static_branch_unlikely(&vgic_v3_cpuif_trap) &&
>> +	    __vgic_v3_perform_cpuif_access(vcpu) == 1)
>> +		return true;
> 
> I think you're now calling this for the 64-bit CP15 access path, which 
> I
> don't think is correct. Maybe have separate handlers for 32-bit v4 
> 64-bit
> accesses?

Good point. The saving grace is that there is no 32bit-capable CPU that
requires GICv3 trapping, nor any 64bit cp15 register in the GICv3
architecture apart form the SGI registers, which are always handled at 
EL1.
So this code is largely academic!

Not providing a handler is the way to go for CP15-64.

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...

WARNING: multiple messages have this Message-ID (diff)

From: Marc Zyngier <maz@kernel.org>
To: Will Deacon <will@kernel.org>
Cc: kvm@vger.kernel.org, kernel-team@android.com,
	linux-arm-kernel@lists.infradead.org, pbonzini@redhat.com,
	kvmarm@lists.cs.columbia.edu
Subject: Re: [PATCH v6 03/12] KVM: arm64: Move early handlers to per-EC handlers
Date: Thu, 30 Sep 2021 17:02:55 +0100	[thread overview]
Message-ID: <2b007cfc37203c84237d4a523cb0cadb@kernel.org> (raw)
In-Reply-To: <20210930133444.GC23809@willie-the-truck>

On 2021-09-30 14:35, Will Deacon wrote:
> On Wed, Sep 22, 2021 at 01:46:55PM +0100, Fuad Tabba wrote:
>> From: Marc Zyngier <maz@kernel.org>

>> +static bool kvm_hyp_handle_cp15(struct kvm_vcpu *vcpu, u64 
>> *exit_code)
>> +{
>> +	if (static_branch_unlikely(&vgic_v3_cpuif_trap) &&
>> +	    __vgic_v3_perform_cpuif_access(vcpu) == 1)
>> +		return true;
> 
> I think you're now calling this for the 64-bit CP15 access path, which 
> I
> don't think is correct. Maybe have separate handlers for 32-bit v4 
> 64-bit
> accesses?

Good point. The saving grace is that there is no 32bit-capable CPU that
requires GICv3 trapping, nor any 64bit cp15 register in the GICv3
architecture apart form the SGI registers, which are always handled at 
EL1.
So this code is largely academic!

Not providing a handler is the way to go for CP15-64.

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm

WARNING: multiple messages have this Message-ID (diff)

From: Marc Zyngier <maz@kernel.org>
To: Will Deacon <will@kernel.org>
Cc: Fuad Tabba <tabba@google.com>,
	kvmarm@lists.cs.columbia.edu, james.morse@arm.com,
	alexandru.elisei@arm.com, suzuki.poulose@arm.com,
	mark.rutland@arm.com, christoffer.dall@arm.com,
	pbonzini@redhat.com, drjones@redhat.com, oupton@google.com,
	qperret@google.com, kvm@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org, kernel-team@android.com
Subject: Re: [PATCH v6 03/12] KVM: arm64: Move early handlers to per-EC handlers
Date: Thu, 30 Sep 2021 17:02:55 +0100	[thread overview]
Message-ID: <2b007cfc37203c84237d4a523cb0cadb@kernel.org> (raw)
In-Reply-To: <20210930133444.GC23809@willie-the-truck>

On 2021-09-30 14:35, Will Deacon wrote:
> On Wed, Sep 22, 2021 at 01:46:55PM +0100, Fuad Tabba wrote:
>> From: Marc Zyngier <maz@kernel.org>

>> +static bool kvm_hyp_handle_cp15(struct kvm_vcpu *vcpu, u64 
>> *exit_code)
>> +{
>> +	if (static_branch_unlikely(&vgic_v3_cpuif_trap) &&
>> +	    __vgic_v3_perform_cpuif_access(vcpu) == 1)
>> +		return true;
> 
> I think you're now calling this for the 64-bit CP15 access path, which 
> I
> don't think is correct. Maybe have separate handlers for 32-bit v4 
> 64-bit
> accesses?

Good point. The saving grace is that there is no 32bit-capable CPU that
requires GICv3 trapping, nor any 64bit cp15 register in the GICv3
architecture apart form the SGI registers, which are always handled at 
EL1.
So this code is largely academic!

Not providing a handler is the way to go for CP15-64.

Thanks,

         M.
-- 
Jazz is not dead. It just smells funny...

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

next prev parent reply	other threads:[~2021-09-30 16:02 UTC|newest]

Thread overview: 90+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-22 12:46 [PATCH v6 00/12] KVM: arm64: Fixed features for protected VMs Fuad Tabba
2021-09-22 12:46 ` Fuad Tabba
2021-09-22 12:46 ` Fuad Tabba
2021-09-22 12:46 ` [PATCH v6 01/12] KVM: arm64: Move __get_fault_info() and co into their own include file Fuad Tabba
2021-09-22 12:46   ` Fuad Tabba
2021-09-22 12:46   ` Fuad Tabba
2021-09-30 13:04   ` Will Deacon
2021-09-30 13:04     ` Will Deacon
2021-09-30 13:04     ` Will Deacon
2021-09-22 12:46 ` [PATCH v6 02/12] KVM: arm64: Don't include switch.h into nvhe/kvm-main.c Fuad Tabba
2021-09-22 12:46   ` Fuad Tabba
2021-09-22 12:46   ` Fuad Tabba
2021-09-30 13:07   ` Will Deacon
2021-09-30 13:07     ` Will Deacon
2021-09-30 13:07     ` Will Deacon
2021-09-22 12:46 ` [PATCH v6 03/12] KVM: arm64: Move early handlers to per-EC handlers Fuad Tabba
2021-09-22 12:46   ` Fuad Tabba
2021-09-22 12:46   ` Fuad Tabba
2021-09-30 13:35   ` Will Deacon
2021-09-30 13:35     ` Will Deacon
2021-09-30 13:35     ` Will Deacon
2021-09-30 16:02     ` Marc Zyngier [this message]
2021-09-30 16:02       ` Marc Zyngier
2021-09-30 16:02       ` Marc Zyngier
2021-09-30 16:27     ` Marc Zyngier
2021-09-30 16:27       ` Marc Zyngier
2021-09-30 16:27       ` Marc Zyngier
2021-09-22 12:46 ` [PATCH v6 04/12] KVM: arm64: Add missing FORCE prerequisite in Makefile Fuad Tabba
2021-09-22 12:46   ` Fuad Tabba
2021-09-22 12:46   ` Fuad Tabba
2021-09-22 14:17   ` Marc Zyngier
2021-09-22 14:17     ` Marc Zyngier
2021-09-22 14:17     ` Marc Zyngier
2021-09-22 12:46 ` [PATCH v6 05/12] KVM: arm64: Pass struct kvm to per-EC handlers Fuad Tabba
2021-09-22 12:46   ` Fuad Tabba
2021-09-22 12:46   ` Fuad Tabba
2021-09-22 12:46 ` [PATCH v6 06/12] KVM: arm64: Add missing field descriptor for MDCR_EL2 Fuad Tabba
2021-09-22 12:46   ` Fuad Tabba
2021-09-22 12:46   ` Fuad Tabba
2021-09-22 12:46 ` [PATCH v6 07/12] KVM: arm64: Simplify masking out MTE in feature id reg Fuad Tabba
2021-09-22 12:46   ` Fuad Tabba
2021-09-22 12:46   ` Fuad Tabba
2021-09-22 12:47 ` [PATCH v6 08/12] KVM: arm64: Add handlers for protected VM System Registers Fuad Tabba
2021-09-22 12:47   ` Fuad Tabba
2021-09-22 12:47   ` Fuad Tabba
2021-10-05  8:52   ` Andrew Jones
2021-10-05  8:52     ` Andrew Jones
2021-10-05  8:52     ` Andrew Jones
2021-10-05 16:43     ` Fuad Tabba
2021-10-05 16:43       ` Fuad Tabba
2021-10-05 16:43       ` Fuad Tabba
2021-10-05  9:53   ` Marc Zyngier
2021-10-05  9:53     ` Marc Zyngier
2021-10-05  9:53     ` Marc Zyngier
2021-10-05 16:49     ` Fuad Tabba
2021-10-05 16:49       ` Fuad Tabba
2021-10-05 16:49       ` Fuad Tabba
2021-09-22 12:47 ` [PATCH v6 09/12] KVM: arm64: Initialize trap registers for protected VMs Fuad Tabba
2021-09-22 12:47   ` Fuad Tabba
2021-09-22 12:47   ` Fuad Tabba
2021-10-05  9:23   ` Marc Zyngier
2021-10-05  9:23     ` Marc Zyngier
2021-10-05  9:23     ` Marc Zyngier
2021-10-05  9:33     ` Fuad Tabba
2021-10-05  9:33       ` Fuad Tabba
2021-10-05  9:33       ` Fuad Tabba
2021-10-06  6:56   ` Andrew Jones
2021-10-06  6:56     ` Andrew Jones
2021-10-06  6:56     ` Andrew Jones
2021-09-22 12:47 ` [PATCH v6 10/12] KVM: arm64: Move sanitized copies of CPU features Fuad Tabba
2021-09-22 12:47   ` Fuad Tabba
2021-09-22 12:47   ` Fuad Tabba
2021-09-22 12:47 ` [PATCH v6 11/12] KVM: arm64: Trap access to pVM restricted features Fuad Tabba
2021-09-22 12:47   ` Fuad Tabba
2021-09-22 12:47   ` Fuad Tabba
2021-10-04 17:27   ` Marc Zyngier
2021-10-04 17:27     ` Marc Zyngier
2021-10-04 17:27     ` Marc Zyngier
2021-10-05  7:20     ` Fuad Tabba
2021-10-05  7:20       ` Fuad Tabba
2021-10-05  7:20       ` Fuad Tabba
2021-09-22 12:47 ` [PATCH v6 12/12] KVM: arm64: Handle protected guests at 32 bits Fuad Tabba
2021-09-22 12:47   ` Fuad Tabba
2021-09-22 12:47   ` Fuad Tabba
2021-10-05  8:48   ` Marc Zyngier
2021-10-05  8:48     ` Marc Zyngier
2021-10-05  8:48     ` Marc Zyngier
2021-10-05  9:05     ` Fuad Tabba
2021-10-05  9:05       ` Fuad Tabba
2021-10-05  9:05       ` Fuad Tabba

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