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From: Marc Zyngier <marc.zyngier@arm.com>
To: Julien Thierry <julien.thierry@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org
Cc: Andre Przywara <andre.przywara@arm.com>,
	Christoffer Dall <christoffer.dall@arm.com>,
	Dave Martin <Dave.Martin@arm.com>,
	Jintack Lim <jintack@cs.columbia.edu>,
	James Morse <james.morse@arm.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>
Subject: Re: [PATCH 16/59] KVM: arm64: nv: Save/Restore vEL2 sysregs
Date: Wed, 3 Jul 2019 14:42:55 +0100	[thread overview]
Message-ID: <7102a9ab-ede8-bd08-ce9b-12e3f36e40e1@arm.com> (raw)
In-Reply-To: <800f3e9a-5b67-951b-34c2-60367c0697f9@arm.com>

On 25/06/2019 09:48, Julien Thierry wrote:
> 
> 
> On 06/21/2019 10:38 AM, Marc Zyngier wrote:
>> From: Andre Przywara <andre.przywara@arm.com>
>>
>> Whenever we need to restore the guest's system registers to the CPU, we
>> now need to take care of the EL2 system registers as well. Most of them
>> are accessed via traps only, but some have an immediate effect and also
>> a guest running in VHE mode would expect them to be accessible via their
>> EL1 encoding, which we do not trap.
>>
>> Split the current __sysreg_{save,restore}_el1_state() functions into
>> handling common sysregs, then differentiate between the guest running in
>> vEL2 and vEL1.
>>
>> For vEL2 we write the virtual EL2 registers with an identical format directly
>> into their EL1 counterpart, and translate the few registers that have a
>> different format for the same effect on the execution when running a
>> non-VHE guest guest hypervisor.
>>
>>   [ Commit message reworked and many bug fixes applied by Marc Zyngier
>>     and Christoffer Dall. ]
>>
>> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
>> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
>> Signed-off-by: Christoffer Dall <christoffer.dall@arm.com>
>> ---
>>  arch/arm64/kvm/hyp/sysreg-sr.c | 160 +++++++++++++++++++++++++++++++--
>>  1 file changed, 153 insertions(+), 7 deletions(-)
>>
>> diff --git a/arch/arm64/kvm/hyp/sysreg-sr.c b/arch/arm64/kvm/hyp/sysreg-sr.c
>> index 62866a68e852..2abb9c3ff24f 100644
>> --- a/arch/arm64/kvm/hyp/sysreg-sr.c
>> +++ b/arch/arm64/kvm/hyp/sysreg-sr.c
> 
> [...]
> 
>> @@ -124,10 +167,91 @@ static void __hyp_text __sysreg_restore_user_state(struct kvm_cpu_context *ctxt)
>>  	write_sysreg(ctxt->sys_regs[TPIDRRO_EL0],	tpidrro_el0);
>>  }
>>  
>> -static void __hyp_text __sysreg_restore_el1_state(struct kvm_cpu_context *ctxt)
>> +static void __sysreg_restore_vel2_state(struct kvm_cpu_context *ctxt)
>>  {
>> +	u64 val;
>> +
>> +	write_sysreg(read_cpuid_id(),			vpidr_el2);
>>  	write_sysreg(ctxt->sys_regs[MPIDR_EL1],		vmpidr_el2);
>> -	write_sysreg(ctxt->sys_regs[CSSELR_EL1],	csselr_el1);
>> +	write_sysreg_el1(ctxt->sys_regs[MAIR_EL2],	SYS_MAIR);
>> +	write_sysreg_el1(ctxt->sys_regs[VBAR_EL2],	SYS_VBAR);
>> +	write_sysreg_el1(ctxt->sys_regs[CONTEXTIDR_EL2],SYS_CONTEXTIDR);
>> +	write_sysreg_el1(ctxt->sys_regs[AMAIR_EL2],	SYS_AMAIR);
>> +
>> +	if (__vcpu_el2_e2h_is_set(ctxt)) {
>> +		/*
>> +		 * In VHE mode those registers are compatible between
>> +		 * EL1 and EL2.
>> +		 */
>> +		write_sysreg_el1(ctxt->sys_regs[SCTLR_EL2],	SYS_SCTLR);
>> +		write_sysreg_el1(ctxt->sys_regs[CPTR_EL2],	SYS_CPACR);
>> +		write_sysreg_el1(ctxt->sys_regs[TTBR0_EL2],	SYS_TTBR0);
>> +		write_sysreg_el1(ctxt->sys_regs[TTBR1_EL2],	SYS_TTBR1);
>> +		write_sysreg_el1(ctxt->sys_regs[TCR_EL2],	SYS_TCR);
>> +		write_sysreg_el1(ctxt->sys_regs[CNTHCTL_EL2],	SYS_CNTKCTL);
>> +	} else {
>> +		write_sysreg_el1(translate_sctlr(ctxt->sys_regs[SCTLR_EL2]),
>> +				 SYS_SCTLR);
>> +		write_sysreg_el1(translate_cptr(ctxt->sys_regs[CPTR_EL2]),
>> +				 SYS_CPACR);
>> +		write_sysreg_el1(translate_ttbr0(ctxt->sys_regs[TTBR0_EL2]),
>> +				 SYS_TTBR0);
>> +		write_sysreg_el1(translate_tcr(ctxt->sys_regs[TCR_EL2]),
>> +				 SYS_TCR);
>> +		write_sysreg_el1(translate_cnthctl(ctxt->sys_regs[CNTHCTL_EL2]),
>> +				 SYS_CNTKCTL);
>> +	}
>> +
>> +	/*
>> +	 * These registers can be modified behind our back by a fault
>> +	 * taken inside vEL2. Save them, always.
>> +	 */
>> +	write_sysreg_el1(ctxt->sys_regs[ESR_EL2],	SYS_ESR);
>> +	write_sysreg_el1(ctxt->sys_regs[AFSR0_EL2],	SYS_AFSR0);
>> +	write_sysreg_el1(ctxt->sys_regs[AFSR1_EL2],	SYS_AFSR1);
>> +	write_sysreg_el1(ctxt->sys_regs[FAR_EL2],	SYS_FAR);
>> +	write_sysreg(ctxt->sys_regs[SP_EL2],		sp_el1);
>> +	write_sysreg_el1(ctxt->sys_regs[ELR_EL2],	SYS_ELR);
>> +
>> +	val = __fixup_spsr_el2_write(ctxt, ctxt->sys_regs[SPSR_EL2]);
>> +	write_sysreg_el1(val,	SYS_SPSR);
>> +}
>> +
>> +static void __hyp_text __sysreg_restore_vel1_state(struct kvm_cpu_context *ctxt)
>> +{
>> +	u64 mpidr;
>> +
>> +	if (has_vhe()) {
>> +		struct kvm_vcpu *vcpu;
>> +
>> +		/*
>> +		 * Warning: this hack only works on VHE, because we only
>> +		 * call this with the *guest* context, which is part of
>> +		 * struct kvm_vcpu. On a host context, you'd get pure junk.
>> +		 */
>> +		vcpu = container_of(ctxt, struct kvm_vcpu, arch.ctxt);
> 
> This seems very fragile, just to find out whether the guest has hyp
> capabilities. It would be at least nice to make sure this is indeed a
> guest context.

Oh come on! It is such a nice hack! ;-) I distinctly remember
Christoffer being >that< close to vomiting when he saw that first.

More seriously, we know what the context is by construction.

> The *clean* way to do it could be to have a pointer to kvm_vcpu in the
> kvm_cpu_context which would be NULL for host contexts.

Funny you mention that. We have the exact opposite (host context
pointing to the running vcpu, and NULL in the guest context). Maybe we
can come up with something that always point to the vcpu, assuming
nothing yet checks for NULL to identify a guest context! ;-)

> Otherwise, I'm under the impression that for a host context,
> ctxt->sys_reg[HCR_EL2] == 0 and that this would also be true for a guest
> without nested virt capability. Could we use something like that here?

Urgh. I think I'd prefer the above suggestion. Or even my hack.

Thanks,

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

  reply	other threads:[~2019-07-03 13:43 UTC|newest]

Thread overview: 176+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-21  9:37 [PATCH 00/59] KVM: arm64: ARMv8.3 Nested Virtualization support Marc Zyngier
2019-06-21  9:37 ` [PATCH 01/59] KVM: arm64: Migrate _elx sysreg accessors to msr_s/mrs_s Marc Zyngier
2019-06-24 11:16   ` Dave Martin
2019-06-24 12:59   ` Alexandru Elisei
2019-07-03 12:32     ` Marc Zyngier
2019-06-21  9:37 ` [PATCH 02/59] KVM: arm64: Move __load_guest_stage2 to kvm_mmu.h Marc Zyngier
2019-06-24 11:19   ` Dave Martin
2019-07-03  9:30     ` Marc Zyngier
2019-07-03 16:13       ` Dave Martin
2019-06-21  9:37 ` [PATCH 03/59] arm64: Add ARM64_HAS_NESTED_VIRT cpufeature Marc Zyngier
2019-06-21 13:08   ` Julien Thierry
2019-06-21 13:22     ` Marc Zyngier
2019-06-21 13:44   ` Suzuki K Poulose
2019-06-24 11:24   ` Dave Martin
2019-06-21  9:37 ` [PATCH 04/59] KVM: arm64: nv: Introduce nested virtualization VCPU feature Marc Zyngier
2019-06-21 13:08   ` Julien Thierry
2019-06-24 11:28   ` Dave Martin
2019-07-03 11:53     ` Marc Zyngier
2019-07-03 16:27       ` Dave Martin
2019-06-24 11:43   ` Dave Martin
2019-07-03 11:56     ` Marc Zyngier
2019-07-03 16:24       ` Dave Martin
2019-06-21  9:37 ` [PATCH 05/59] KVM: arm64: nv: Reset VCPU to EL2 registers if VCPU nested virt is set Marc Zyngier
2019-06-24 10:19   ` Suzuki K Poulose
2019-06-24 11:38   ` Dave Martin
2019-06-21  9:37 ` [PATCH 06/59] KVM: arm64: nv: Allow userspace to set PSR_MODE_EL2x Marc Zyngier
2019-06-21 13:24   ` Julien Thierry
2019-06-21 13:50     ` Marc Zyngier
2019-06-24 12:48       ` Dave Martin
2019-07-03  9:21         ` Marc Zyngier
2019-07-04 10:00           ` Dave Martin
2019-06-21  9:37 ` [PATCH 07/59] KVM: arm64: nv: Add EL2 system registers to vcpu context Marc Zyngier
2019-06-24 12:54   ` Dave Martin
2019-07-03 12:20     ` Marc Zyngier
2019-07-03 16:31       ` Dave Martin
2019-06-24 15:47   ` Alexandru Elisei
2019-07-03 13:20     ` Marc Zyngier
2019-07-03 16:01       ` Marc Zyngier
2019-07-01 16:36   ` Suzuki K Poulose
2019-06-21  9:37 ` [PATCH 08/59] KVM: arm64: nv: Reset VMPIDR_EL2 and VPIDR_EL2 to sane values Marc Zyngier
2019-06-24 12:59   ` Dave Martin
2019-06-21  9:37 ` [PATCH 09/59] KVM: arm64: nv: Add nested virt VCPU primitives for vEL2 VCPU state Marc Zyngier
2019-06-24 13:08   ` Dave Martin
2019-06-21  9:37 ` [PATCH 10/59] KVM: arm64: nv: Support virtual EL2 exceptions Marc Zyngier
2019-07-08 13:56   ` Steven Price
2019-06-21  9:37 ` [PATCH 11/59] KVM: arm64: nv: Inject HVC exceptions to the virtual EL2 Marc Zyngier
2019-06-25 13:13   ` Alexandru Elisei
2019-07-03 14:16     ` Marc Zyngier
2019-07-30 14:08     ` Alexandru Elisei
2019-06-21  9:37 ` [PATCH 12/59] KVM: arm64: nv: Handle trapped ERET from " Marc Zyngier
2019-07-02 12:00   ` Alexandru Elisei
2019-06-21  9:37 ` [PATCH 13/59] KVM: arm64: nv: Handle virtual EL2 registers in vcpu_read/write_sys_reg() Marc Zyngier
2019-06-24 12:42   ` Julien Thierry
2019-06-25 14:02     ` Alexandru Elisei
2019-07-03 12:15     ` Marc Zyngier
2019-07-03 15:21       ` Julien Thierry
2019-06-25 15:18   ` Alexandru Elisei
2019-07-01  9:58     ` Alexandru Elisei
2019-07-03 15:59     ` Marc Zyngier
2019-07-03 16:32       ` Alexandru Elisei
2019-07-04 14:39         ` Marc Zyngier
2019-06-26 15:04   ` Alexandru Elisei
2019-07-04 15:05     ` Marc Zyngier
2019-07-01 12:10   ` Alexandru Elisei
2019-06-21  9:37 ` [PATCH 14/59] KVM: arm64: nv: Handle SPSR_EL2 specially Marc Zyngier
2019-06-21  9:37 ` [PATCH 15/59] KVM: arm64: nv: Refactor vcpu_{read,write}_sys_reg Marc Zyngier
2019-06-24 15:07   ` Julien Thierry
2019-07-03 13:09     ` Marc Zyngier
2019-06-27  9:21   ` Alexandru Elisei
2019-07-04 15:15     ` Marc Zyngier
2019-06-21  9:38 ` [PATCH 16/59] KVM: arm64: nv: Save/Restore vEL2 sysregs Marc Zyngier
2019-06-25  8:48   ` Julien Thierry
2019-07-03 13:42     ` Marc Zyngier [this message]
2019-07-01 12:09   ` Alexandru Elisei
2019-08-21 11:57   ` Alexandru Elisei
2019-06-21  9:38 ` [PATCH 17/59] KVM: arm64: nv: Emulate PSTATE.M for a guest hypervisor Marc Zyngier
2019-06-21  9:38 ` [PATCH 18/59] KVM: arm64: nv: Trap EL1 VM register accesses in virtual EL2 Marc Zyngier
2019-07-01 16:12   ` Alexandru Elisei
2019-06-21  9:38 ` [PATCH 19/59] KVM: arm64: nv: Trap SPSR_EL1, ELR_EL1 and VBAR_EL1 from " Marc Zyngier
2019-06-21  9:38 ` [PATCH 20/59] KVM: arm64: nv: Trap CPACR_EL1 access in " Marc Zyngier
2019-07-01 16:40   ` Alexandru Elisei
2019-06-21  9:38 ` [PATCH 21/59] KVM: arm64: nv: Set a handler for the system instruction traps Marc Zyngier
2019-06-25 12:55   ` Julien Thierry
2019-07-03 14:15     ` Marc Zyngier
2019-06-21  9:38 ` [PATCH 22/59] KVM: arm64: nv: Handle PSCI call via smc from the guest Marc Zyngier
2019-06-21  9:38 ` [PATCH 23/59] KVM: arm64: nv: Respect virtual HCR_EL2.TWX setting Marc Zyngier
2019-06-25 14:19   ` Julien Thierry
2019-07-02 12:54     ` Alexandru Elisei
2019-07-03 14:18     ` Marc Zyngier
2019-06-21  9:38 ` [PATCH 24/59] KVM: arm64: nv: Respect virtual CPTR_EL2.TFP setting Marc Zyngier
2019-06-21  9:38 ` [PATCH 25/59] KVM: arm64: nv: Don't expose SVE to nested guests Marc Zyngier
2019-06-21  9:38 ` [PATCH 26/59] KVM: arm64: nv: Respect the virtual HCR_EL2.NV bit setting Marc Zyngier
2019-06-26  5:31   ` Julien Thierry
2019-07-03 16:31     ` Marc Zyngier
2019-06-21  9:38 ` [PATCH 27/59] KVM: arm64: nv: Respect virtual HCR_EL2.TVM and TRVM settings Marc Zyngier
2019-06-26  6:55   ` Julien Thierry
2019-07-04 14:57     ` Marc Zyngier
2019-06-21  9:38 ` [PATCH 28/59] KVM: arm64: nv: Respect the virtual HCR_EL2.NV1 bit setting Marc Zyngier
2019-06-26  7:23   ` Julien Thierry
2019-07-02 16:32   ` Alexandru Elisei
2019-07-03  9:10     ` Alexandru Elisei
2019-06-21  9:38 ` [PATCH 29/59] KVM: arm64: nv: Emulate EL12 register accesses from the virtual EL2 Marc Zyngier
2019-07-03  9:16   ` Alexandru Elisei
2019-06-21  9:38 ` [PATCH 30/59] KVM: arm64: nv: Configure HCR_EL2 for nested virtualization Marc Zyngier
2019-06-21  9:38 ` [PATCH 31/59] KVM: arm64: nv: Only toggle cache for virtual EL2 when SCTLR_EL2 changes Marc Zyngier
2019-06-21  9:38 ` [PATCH 32/59] KVM: arm64: nv: Hide RAS from nested guests Marc Zyngier
2019-07-03 13:59   ` Alexandru Elisei
2019-06-21  9:38 ` [PATCH 33/59] KVM: arm64: nv: Pretend we only support larger-than-host page sizes Marc Zyngier
2019-07-03 14:13   ` Alexandru Elisei
2019-06-21  9:38 ` [PATCH 34/59] KVM: arm/arm64: nv: Factor out stage 2 page table data from struct kvm Marc Zyngier
2019-07-03 15:52   ` Alexandru Elisei
2019-06-21  9:38 ` [PATCH 35/59] KVM: arm/arm64: nv: Support multiple nested stage 2 mmu structures Marc Zyngier
2019-06-25 12:19   ` Alexandru Elisei
2019-07-03 13:47     ` Marc Zyngier
2019-06-27 13:15   ` Julien Thierry
2019-07-04 15:51   ` Alexandru Elisei
2020-01-05 11:35     ` Marc Zyngier
2020-01-06 16:31       ` Alexandru Elisei
2019-06-21  9:38 ` [PATCH 36/59] KVM: arm64: nv: Implement nested Stage-2 page table walk logic Marc Zyngier
2019-06-21  9:38 ` [PATCH 37/59] KVM: arm64: nv: Handle shadow stage 2 page faults Marc Zyngier
2019-07-05 14:28   ` Alexandru Elisei
2019-06-21  9:38 ` [PATCH 38/59] KVM: arm64: nv: Unmap/flush shadow stage 2 page tables Marc Zyngier
2019-07-01  8:03   ` Julien Thierry
2019-06-21  9:38 ` [PATCH 39/59] KVM: arm64: nv: Move last_vcpu_ran to be per s2 mmu Marc Zyngier
2019-07-01  9:10   ` Julien Thierry
2019-07-05 15:28   ` Alexandru Elisei
2019-06-21  9:38 ` [PATCH 40/59] KVM: arm64: nv: Don't always start an S2 MMU search from the beginning Marc Zyngier
2019-07-09  9:59   ` Alexandru Elisei
2019-06-21  9:38 ` [PATCH 41/59] KVM: arm64: nv: Introduce sys_reg_desc.forward_trap Marc Zyngier
2019-06-21  9:38 ` [PATCH 42/59] KVM: arm64: nv: Rework the system instruction emulation framework Marc Zyngier
2019-06-21  9:38 ` [PATCH 43/59] KVM: arm64: nv: Trap and emulate AT instructions from virtual EL2 Marc Zyngier
2019-07-01 15:45   ` Julien Thierry
2019-07-09 13:20   ` Alexandru Elisei
2019-07-18 12:13     ` Tomasz Nowicki
     [not found]       ` <6537c8d2-3bda-788e-8861-b70971a625cb@arm.com>
2019-07-18 12:59         ` Tomasz Nowicki
2019-07-24 10:25   ` Tomasz Nowicki
2019-07-24 12:39     ` Marc Zyngier
2019-07-24 13:56       ` Tomasz Nowicki
2019-06-21  9:38 ` [PATCH 44/59] KVM: arm64: nv: Trap and emulate TLBI " Marc Zyngier
2019-07-02 12:37   ` Julien Thierry
2019-07-10 10:15   ` Alexandru Elisei
2019-06-21  9:38 ` [PATCH 45/59] KVM: arm64: nv: Handle traps for timer _EL02 and _EL2 sysregs accessors Marc Zyngier
2019-06-21  9:38 ` [PATCH 46/59] KVM: arm64: nv: arch_timer: Support hyp timer emulation Marc Zyngier
2019-07-10 16:23   ` Alexandru Elisei
2019-06-21  9:38 ` [PATCH 47/59] KVM: arm64: nv: Propagate CNTVOFF_EL2 to the virtual EL1 timer Marc Zyngier
2019-08-08  9:34   ` Alexandru Elisei
2019-06-21  9:38 ` [PATCH 48/59] KVM: arm64: nv: Load timer before the GIC Marc Zyngier
2019-07-11 13:17   ` Alexandru Elisei
2019-06-21  9:38 ` [PATCH 49/59] KVM: arm64: nv: vgic-v3: Take cpu_if pointer directly instead of vcpu Marc Zyngier
2019-06-21  9:38 ` [PATCH 50/59] KVM: arm64: nv: Nested GICv3 Support Marc Zyngier
2019-07-16 11:41   ` Alexandru Elisei
2019-06-21  9:38 ` [PATCH 51/59] KVM: arm64: nv: vgic: Emulate the HW bit in software Marc Zyngier
2019-06-21  9:38 ` [PATCH 52/59] KVM: arm64: nv: vgic: Allow userland to set VGIC maintenance IRQ Marc Zyngier
2019-07-04  7:38   ` Julien Thierry
2019-07-04  9:01     ` Andre Przywara
2019-07-04  9:04       ` Julien Thierry
2019-06-21  9:38 ` [PATCH 53/59] KVM: arm64: nv: Implement maintenance interrupt forwarding Marc Zyngier
2019-07-04  8:06   ` Julien Thierry
2019-07-16 16:35   ` Alexandru Elisei
2019-06-21  9:38 ` [PATCH 54/59] KVM: arm64: nv: Add nested GICv3 tracepoints Marc Zyngier
2019-06-21  9:38 ` [PATCH 55/59] arm64: KVM: nv: Add handling of EL2-specific timer registers Marc Zyngier
2019-07-11 12:35   ` Alexandru Elisei
2019-07-17 10:19   ` Alexandru Elisei
2019-06-21  9:38 ` [PATCH 56/59] arm64: KVM: nv: Honor SCTLR_EL2.SPAN on entering vEL2 Marc Zyngier
2019-06-21  9:38 ` [PATCH 57/59] arm64: KVM: nv: Handle SCTLR_EL2 RES0/RES1 bits Marc Zyngier
2019-06-21  9:38 ` [PATCH 58/59] arm64: KVM: nv: Restrict S2 RD/WR permissions to match the guest's Marc Zyngier
2019-06-21  9:38 ` [PATCH 59/59] arm64: KVM: nv: Allow userspace to request KVM_ARM_VCPU_NESTED_VIRT Marc Zyngier
     [not found] ` <CANW9uyssDm_0ysC_pnvhHRrnsmFZik+3_ENmFz7L2GCmtH09fw@mail.gmail.com>
2019-06-21 11:21   ` [PATCH 00/59] KVM: arm64: ARMv8.3 Nested Virtualization support Marc Zyngier
2019-08-02 10:11 ` Alexandru Elisei
2019-08-02 10:30   ` Andrew Jones
2019-08-09 10:01   ` Alexandru Elisei
2019-08-09 11:44     ` Andrew Jones
2019-08-09 12:00       ` Alexandru Elisei
2019-08-09 13:00         ` Andrew Jones
2019-08-22 11:57     ` Alexandru Elisei
2019-08-22 15:32       ` Alexandru Elisei

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