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From: Alexandru Elisei <alexandru.elisei@arm.com>
To: Marc Zyngier <maz@kernel.org>
Cc: linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org,
	Andre Przywara <andre.przywara@arm.com>,
	Christoffer Dall <christoffer.dall@arm.com>,
	Jintack Lim <jintack@cs.columbia.edu>,
	Haibo Xu <haibo.xu@linaro.org>,
	Ganapatrao Kulkarni <gankulkarni@os.amperecomputing.com>,
	Chase Conklin <chase.conklin@arm.com>,
	"Russell King (Oracle)" <linux@armlinux.org.uk>,
	James Morse <james.morse@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	karl.heubaum@oracle.com, mihai.carabas@oracle.com,
	miguel.luis@oracle.com, kernel-team@android.com
Subject: Re: [PATCH v6 18/64] KVM: arm64: nv: Trap EL1 VM register accesses in virtual EL2
Date: Thu, 3 Feb 2022 17:11:16 +0000	[thread overview]
Message-ID: <YfwMtP/McwEJApy2@monolith.localdoman> (raw)
In-Reply-To: <20220128121912.509006-19-maz@kernel.org>

Hi Marc,

On Fri, Jan 28, 2022 at 12:18:26PM +0000, Marc Zyngier wrote:
> From: Christoffer Dall <christoffer.dall@linaro.org>
> 
> When running in virtual EL2 mode, we actually run the hardware in EL1
> and therefore have to use the EL1 registers to ensure correct operation.
> 
> By setting the HCR.TVM and HCR.TVRM we ensure that the virtual EL2 mode
> doesn't shoot itself in the foot when setting up what it believes to be
> a different mode's system register state (for example when preparing to
> switch to a VM).
> 
> We can leverage the existing sysregs infrastructure to support trapped
> accesses to these registers.
> 
> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
> ---
>  arch/arm64/kvm/hyp/include/hyp/switch.h |  4 +---
>  arch/arm64/kvm/hyp/nvhe/switch.c        |  2 +-
>  arch/arm64/kvm/hyp/vhe/switch.c         |  7 ++++++-
>  arch/arm64/kvm/sys_regs.c               | 19 ++++++++++++++++---
>  4 files changed, 24 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/arm64/kvm/hyp/include/hyp/switch.h b/arch/arm64/kvm/hyp/include/hyp/switch.h
> index 58e14f8ead23..49c3b9eb09d7 100644
> --- a/arch/arm64/kvm/hyp/include/hyp/switch.h
> +++ b/arch/arm64/kvm/hyp/include/hyp/switch.h
> @@ -110,10 +110,8 @@ static inline void __deactivate_traps_common(struct kvm_vcpu *vcpu)
>  		write_sysreg(0, pmuserenr_el0);
>  }
>  
> -static inline void ___activate_traps(struct kvm_vcpu *vcpu)
> +static inline void ___activate_traps(struct kvm_vcpu *vcpu, u64 hcr)
>  {
> -	u64 hcr = vcpu->arch.hcr_el2;
> -
>  	if (cpus_have_final_cap(ARM64_WORKAROUND_CAVIUM_TX2_219_TVM))
>  		hcr |= HCR_TVM;
>  
> diff --git a/arch/arm64/kvm/hyp/nvhe/switch.c b/arch/arm64/kvm/hyp/nvhe/switch.c
> index 6410d21d8695..61a5627fd456 100644
> --- a/arch/arm64/kvm/hyp/nvhe/switch.c
> +++ b/arch/arm64/kvm/hyp/nvhe/switch.c
> @@ -38,7 +38,7 @@ static void __activate_traps(struct kvm_vcpu *vcpu)
>  {
>  	u64 val;
>  
> -	___activate_traps(vcpu);
> +	___activate_traps(vcpu, vcpu->arch.hcr_el2);
>  	__activate_traps_common(vcpu);
>  
>  	val = vcpu->arch.cptr_el2;
> diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c
> index 82ddaebe66de..6ed9e4893a02 100644
> --- a/arch/arm64/kvm/hyp/vhe/switch.c
> +++ b/arch/arm64/kvm/hyp/vhe/switch.c
> @@ -32,9 +32,14 @@ DEFINE_PER_CPU(unsigned long, kvm_hyp_vector);
>  
>  static void __activate_traps(struct kvm_vcpu *vcpu)
>  {
> +	u64 hcr = vcpu->arch.hcr_el2;
>  	u64 val;
>  
> -	___activate_traps(vcpu);
> +	/* Trap VM sysreg accesses if an EL2 guest is not using VHE. */
> +	if (vcpu_is_el2(vcpu) && !vcpu_el2_e2h_is_set(vcpu))
> +		hcr |= HCR_TVM | HCR_TRVM;
> +
> +	___activate_traps(vcpu, hcr);
>  
>  	val = read_sysreg(cpacr_el1);
>  	val |= CPACR_EL1_TTA;
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 102bc4906723..9d3520f1d17a 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -322,8 +322,15 @@ static void get_access_mask(const struct sys_reg_desc *r, u64 *mask, u64 *shift)
>  
>  /*
>   * Generic accessor for VM registers. Only called as long as HCR_TVM
> - * is set. If the guest enables the MMU, we stop trapping the VM
> - * sys_regs and leave it in complete control of the caches.
> + * is set.
> + *
> + * This is set in two cases: either (1) we're running at vEL2, or (2)
> + * we're running at EL1 and the guest has its MMU off.
> + *
> + * (1) TVM/TRVM is set, as we need to virtualise some of the VM
> + * registers for the guest hypervisor
> + * (2) Once the guest enables the MMU, we stop trapping the VM sys_regs
> + * and leave it in complete control of the caches.
>   */
>  static bool access_vm_reg(struct kvm_vcpu *vcpu,
>  			  struct sys_reg_params *p,
> @@ -332,7 +339,13 @@ static bool access_vm_reg(struct kvm_vcpu *vcpu,
>  	bool was_enabled = vcpu_has_cache_enabled(vcpu);
>  	u64 val, mask, shift;
>  
> -	BUG_ON(!p->is_write);
> +	/* We don't expect TRVM on the host */

I don't get what that means. Isn't KVM setting HCR_EL2.TRVM to trap reads?

Other than that, the patch looks good:

Reviewed-by: Alexandru Elisei <alexandru.elisei@arm.com>

Thanks,
Alex

> +	BUG_ON(!vcpu_is_el2(vcpu) && !p->is_write);
> +
> +	if (!p->is_write) {
> +		p->regval = vcpu_read_sys_reg(vcpu, r->reg);
> +		return true;
> +	}
>  
>  	get_access_mask(r, &mask, &shift);
>  
> -- 
> 2.30.2
> 

  parent reply	other threads:[~2022-02-03 17:11 UTC|newest]

Thread overview: 126+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-28 12:18 [PATCH v6 00/64] KVM: arm64: ARMv8.3/8.4 Nested Virtualization support Marc Zyngier
2022-01-28 12:18 ` [PATCH v6 01/64] arm64: Add ARM64_HAS_NESTED_VIRT cpufeature Marc Zyngier
2022-02-01 14:22   ` Russell King (Oracle)
2022-01-28 12:18 ` [PATCH v6 02/64] KVM: arm64: nv: Introduce nested virtualization VCPU feature Marc Zyngier
2022-01-28 12:18 ` [PATCH v6 03/64] KVM: arm64: nv: Reset VCPU to EL2 registers if VCPU nested virt is set Marc Zyngier
2022-02-02 11:40   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 04/64] KVM: arm64: nv: Allow userspace to set PSR_MODE_EL2x Marc Zyngier
2022-02-02 11:53   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 05/64] KVM: arm64: nv: Add EL2 system registers to vcpu context Marc Zyngier
2022-02-11 16:35   ` Miguel Luis
2022-01-28 12:18 ` [PATCH v6 06/64] KVM: arm64: nv: Add nested virt VCPU primitives for vEL2 VCPU state Marc Zyngier
2022-02-02 12:10   ` Alexandru Elisei
2022-02-14 12:39   ` Miguel Luis
2022-02-14 14:20     ` Marc Zyngier
2022-01-28 12:18 ` [PATCH v6 07/64] KVM: arm64: nv: Handle HCR_EL2.NV system register traps Marc Zyngier
2022-02-01 14:32   ` Russell King (Oracle)
2022-01-28 12:18 ` [PATCH v6 08/64] KVM: arm64: nv: Reset VMPIDR_EL2 and VPIDR_EL2 to sane values Marc Zyngier
2022-01-28 12:18 ` [PATCH v6 09/64] KVM: arm64: nv: Support virtual EL2 exceptions Marc Zyngier
2022-02-02 15:23   ` Alexandru Elisei
2022-02-03 17:43     ` Marc Zyngier
2022-02-04 11:47       ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 10/64] KVM: arm64: nv: Inject HVC exceptions to the virtual EL2 Marc Zyngier
2022-01-28 12:18 ` [PATCH v6 11/64] KVM: arm64: nv: Handle trapped ERET from " Marc Zyngier
2022-01-28 12:18 ` [PATCH v6 12/64] KVM: arm64: nv: Add non-VHE-EL2->EL1 translation helpers Marc Zyngier
2022-02-01 16:37   ` Russell King (Oracle)
2022-02-02 17:08   ` Alexandru Elisei
2022-02-03 18:29     ` Marc Zyngier
2022-02-04 12:05       ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 13/64] KVM: arm64: nv: Handle virtual EL2 registers in vcpu_read/write_sys_reg() Marc Zyngier
2022-02-01 16:40   ` Russell King (Oracle)
2022-01-28 12:18 ` [PATCH v6 14/64] KVM: arm64: nv: Handle SPSR_EL2 specially Marc Zyngier
2022-02-01 16:43   ` Russell King (Oracle)
2022-01-28 12:18 ` [PATCH v6 15/64] KVM: arm64: nv: Handle HCR_EL2.E2H specially Marc Zyngier
2022-02-01 16:51   ` Russell King (Oracle)
2022-02-01 18:17     ` Marc Zyngier
2022-01-28 12:18 ` [PATCH v6 16/64] KVM: arm64: nv: Save/Restore vEL2 sysregs Marc Zyngier
2022-02-03 15:14   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 17/64] KVM: arm64: nv: Emulate PSTATE.M for a guest hypervisor Marc Zyngier
2022-02-01 18:06   ` Russell King (Oracle)
2022-02-03 15:53   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 18/64] KVM: arm64: nv: Trap EL1 VM register accesses in virtual EL2 Marc Zyngier
2022-02-01 18:08   ` Russell King (Oracle)
2022-02-03 17:11   ` Alexandru Elisei [this message]
2022-01-28 12:18 ` [PATCH v6 19/64] KVM: arm64: nv: Trap SPSR_EL1, ELR_EL1 and VBAR_EL1 from " Marc Zyngier
2022-02-01 18:13   ` Russell King (Oracle)
2022-02-03 17:27   ` Alexandru Elisei
2022-02-04 10:58   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 20/64] KVM: arm64: nv: Trap CPACR_EL1 access in " Marc Zyngier
2022-02-04 11:10   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 21/64] KVM: arm64: nv: Handle PSCI call via smc from the guest Marc Zyngier
2022-02-04 14:02   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 22/64] KVM: arm64: nv: Respect virtual HCR_EL2.TWX setting Marc Zyngier
2022-02-04 15:40   ` Alexandru Elisei
2022-02-04 16:01     ` Alexandru Elisei
2022-02-07 15:38     ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 23/64] KVM: arm64: nv: Respect virtual CPTR_EL2.{TFP,FPEN} settings Marc Zyngier
2022-01-28 12:18 ` [PATCH v6 24/64] KVM: arm64: nv: Respect the virtual HCR_EL2.NV bit setting Marc Zyngier
2022-02-07 15:33   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 25/64] KVM: arm64: nv: Respect virtual HCR_EL2.TVM and TRVM settings Marc Zyngier
2022-02-07 16:18   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 26/64] KVM: arm64: nv: Respect the virtual HCR_EL2.NV1 bit setting Marc Zyngier
2022-02-07 16:36   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 27/64] KVM: arm64: nv: Allow a sysreg to be hidden from userspace only Marc Zyngier
2022-02-08 14:36   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 28/64] KVM: arm64: nv: Emulate EL12 register accesses from the virtual EL2 Marc Zyngier
2022-02-08 15:35   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 29/64] KVM: arm64: nv: Forward debug traps to the nested guest Marc Zyngier
2022-02-09 11:04   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 30/64] KVM: arm64: nv: Configure HCR_EL2 for nested virtualization Marc Zyngier
2022-02-09 16:41   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 31/64] KVM: arm64: nv: Only toggle cache for virtual EL2 when SCTLR_EL2 changes Marc Zyngier
2022-02-09 16:56   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 32/64] KVM: arm64: nv: Filter out unsupported features from ID regs Marc Zyngier
2022-02-09 17:33   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 33/64] KVM: arm64: nv: Hide RAS from nested guests Marc Zyngier
2022-01-28 12:18 ` [PATCH v6 34/64] KVM: arm64: nv: Support multiple nested Stage-2 mmu structures Marc Zyngier
2022-02-16 16:12   ` Alexandru Elisei
2022-02-24 14:25   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 35/64] KVM: arm64: nv: Implement nested Stage-2 page table walk logic Marc Zyngier
2022-01-28 12:18 ` [PATCH v6 36/64] KVM: arm64: nv: Handle shadow stage 2 page faults Marc Zyngier
2022-02-17 15:23   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 37/64] KVM: arm64: nv: Restrict S2 RD/WR permissions to match the guest's Marc Zyngier
2022-02-17 16:29   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 38/64] KVM: arm64: nv: Unmap/flush shadow stage 2 page tables Marc Zyngier
2022-02-22 16:13   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 39/64] KVM: arm64: nv: Set a handler for the system instruction traps Marc Zyngier
2022-02-24 11:59   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 40/64] KVM: arm64: nv: Trap and emulate AT instructions from virtual EL2 Marc Zyngier
2022-02-24 15:39   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 41/64] KVM: arm64: nv: Trap and emulate TLBI " Marc Zyngier
2022-02-24 15:56   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 42/64] KVM: arm64: nv: Fold guest's HCR_EL2 configuration into the host's Marc Zyngier
2022-02-25 13:45   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 43/64] KVM: arm64: nv: arch_timer: Support hyp timer emulation Marc Zyngier
2022-03-07 14:52   ` Alexandru Elisei
2022-03-07 15:48     ` Marc Zyngier
2022-03-07 16:28       ` Alexandru Elisei
2022-03-07 16:52         ` Marc Zyngier
2022-03-07 17:13           ` Alexandru Elisei
2022-03-07 15:23   ` Alexandru Elisei
2022-03-07 15:44     ` Marc Zyngier
2022-03-07 16:24       ` Alexandru Elisei
2022-03-07 16:40         ` Marc Zyngier
2022-01-28 12:18 ` [PATCH v6 44/64] KVM: arm64: nv: Add handling of EL2-specific timer registers Marc Zyngier
2022-03-07 16:01   ` Alexandru Elisei
2022-01-28 12:18 ` [PATCH v6 45/64] KVM: arm64: nv: Load timer before the GIC Marc Zyngier
2022-01-28 12:18 ` [PATCH v6 46/64] KVM: arm64: nv: Nested GICv3 Support Marc Zyngier
2022-01-28 12:18 ` [PATCH v6 47/64] KVM: arm64: nv: Don't load the GICv4 context on entering a nested guest Marc Zyngier
2022-01-28 12:18 ` [PATCH v6 48/64] KVM: arm64: nv: vgic: Emulate the HW bit in software Marc Zyngier
2022-01-28 12:18 ` [PATCH v6 49/64] KVM: arm64: nv: vgic: Allow userland to set VGIC maintenance IRQ Marc Zyngier
2022-01-28 12:18 ` [PATCH v6 50/64] KVM: arm64: nv: Implement maintenance interrupt forwarding Marc Zyngier
2022-01-28 12:18 ` [PATCH v6 51/64] KVM: arm64: nv: Add nested GICv3 tracepoints Marc Zyngier
2022-01-28 12:19 ` [PATCH v6 52/64] KVM: arm64: nv: Allow userspace to request KVM_ARM_VCPU_NESTED_VIRT Marc Zyngier
2022-01-28 12:19 ` [PATCH v6 53/64] KVM: arm64: nv: Add handling of ARMv8.4-TTL TLB invalidation Marc Zyngier
2022-01-28 12:19 ` [PATCH v6 54/64] KVM: arm64: nv: Invalidate TLBs based on shadow S2 TTL-like information Marc Zyngier
2022-01-28 12:19 ` [PATCH v6 55/64] KVM: arm64: nv: Tag shadow S2 entries with nested level Marc Zyngier
2022-01-28 12:19 ` [PATCH v6 56/64] KVM: arm64: nv: Add include containing the VNCR_EL2 offsets Marc Zyngier
2022-01-28 12:19 ` [PATCH v6 57/64] KVM: arm64: nv: Map VNCR-capable registers to a separate page Marc Zyngier
2022-01-28 12:19 ` [PATCH v6 58/64] KVM: arm64: nv: Move nested vgic state into the sysreg file Marc Zyngier
2022-01-28 12:19 ` [PATCH v6 59/64] KVM: arm64: Add ARMv8.4 Enhanced Nested Virt cpufeature Marc Zyngier
2022-01-28 12:19 ` [PATCH v6 60/64] KVM: arm64: nv: Sync nested timer state with ARMv8.4 Marc Zyngier
2022-04-01 17:51   ` Chase Conklin
2022-01-28 12:19 ` [PATCH v6 61/64] KVM: arm64: nv: Allocate VNCR page when required Marc Zyngier
2022-01-28 12:19 ` [PATCH v6 62/64] KVM: arm64: nv: Enable ARMv8.4-NV support Marc Zyngier
2022-01-28 12:19 ` [PATCH v6 63/64] KVM: arm64: nv: Fast-track 'InHost' exception returns Marc Zyngier
2022-01-28 12:19 ` [PATCH v6 64/64] KVM: arm64: nv: Fast-track EL1 TLBIs for VHE guests Marc Zyngier

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