Re: [RFC 08/55] KVM: arm64: Set virtual EL2 context depending on the guest exception level

Path	csiph.com!aioe.org!bofh.it!news.nic.it!robomod
From	Christoffer Dall <cdall@linaro.org>
Newsgroups	linux.kernel
Subject	Re: [RFC 08/55] KVM: arm64: Set virtual EL2 context depending on the guest exception level
Date	Wed, 22 Feb 2017 12:20:02 +0100
Message-ID	<tdD7I-R8-17@gated-at.bofh.it> (permalink)
References	<sXBCV-wl-3@gated-at.bofh.it> <sXBCV-wl-17@gated-at.bofh.it>
Dkim-Signature	v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=JkP9pqFrlSvNOkbGnvyXAv24lfkObC3YXWprC/W+mmI=; b=gHvaudQ/iap22EWBHHikqq6BFpY61klVcNu8ReIVAhQZWrN8PF/lJb25d84px3yOHT 83RTG5CqbP2EJhUZEzqsWbwT2/E1fSyXiBMfgYz7i7fTWjRKWkOgtfXWBSIEbB18dSE8 FtiCkRpEt+re28kf/DufpgvJfOcvZ7vlVW0B0=
X-Google-Dkim-Signature	v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=JkP9pqFrlSvNOkbGnvyXAv24lfkObC3YXWprC/W+mmI=; b=qmr/Ty8ctWe5GsdlXvuRbZjMV3tlrpvcW2og939sbQorkMcNRFICF3a4ZzPyOo32HV N9CVVbvVhZrKJhMaTOMEflRsSoBr4UyeSNO8eB0OhKr+VmnC/l5Hj+Oadm/MZPqrdfBR S2rniXZus4Bu7ovlfNTXZJddAaNN//0cjduUJ6kcRkMDFmwiSOSWpLE8g8Iu0paISZ9o nZvbKfIubADQESG4zGcn/ogiSn2jZtA3Y0AhBCPq/WSPCSlPezl6FO3gpCcLYCfydIIs 290gvUGIKgdVwH2OmLwohiqFLvH+8udSQnSgy8cDjzUju5o93IEkOWYF7YlxFJ69BmkL mVQA==
X-Gm-Message-State	AMke39n0tV2VikTQuCLNmh6KF9BE3R6xhjxzR1EpeHgLoBbaitALcOxV7c2JvOcesHYwu574
X-Received	by 10.28.20.209 with SMTP id 200mr1966414wmu.64.1487762097919; Wed, 22 Feb 2017 03:14:57 -0800 (PST)
MIME-Version	1.0
Content-Type	text/plain; charset=us-ascii
Content-Disposition	inline
User-Agent	Mutt/1.5.21 (2010-09-15)
Sender	robomod@news.nic.it
List-ID	<linux-kernel.vger.kernel.org>
X-Mailing-List	linux-kernel@vger.kernel.org
Approved	robomod@news.nic.it
Lines	78
Organization	linux.* mail to news gateway
X-Original-Cc	christoffer.dall@linaro.org, marc.zyngier@arm.com, pbonzini@redhat.com, rkrcmar@redhat.com, linux@armlinux.org.uk, catalin.marinas@arm.com, will.deacon@arm.com, vladimir.murzin@arm.com, suzuki.poulose@arm.com, mark.rutland@arm.com, james.morse@arm.com, lorenzo.pieralisi@arm.com, kevin.brodsky@arm.com, wcohen@redhat.com, shankerd@codeaurora.org, geoff@infradead.org, andre.przywara@arm.com, eric.auger@redhat.com, anna-maria@linutronix.de, shihwei@cs.columbia.edu, linux-arm-kernel@lists.infradead.org, kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org, linux-kernel@vger.kernel.org
X-Original-Date	Wed, 22 Feb 2017 12:14:45 +0100
X-Original-Message-ID	<20170222111445.GD26976@cbox>
X-Original-References	<1483943091-1364-1-git-send-email-jintack@cs.columbia.edu> <1483943091-1364-9-git-send-email-jintack@cs.columbia.edu>
X-Original-Sender	linux-kernel-owner@vger.kernel.org
Xref	csiph.com linux.kernel:1586073

Show key headers only | View raw

On Mon, Jan 09, 2017 at 01:24:04AM -0500, Jintack Lim wrote:
> From: Christoffer Dall <christoffer.dall@linaro.org>
> 
> Set up virutal EL2 context to hardware if the guest exception level is
> EL2.
> 
> Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
> Signed-off-by: Jintack Lim <jintack@cs.columbia.edu>
> ---
>  arch/arm64/kvm/context.c | 32 ++++++++++++++++++++++++++------
>  1 file changed, 26 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/arm64/kvm/context.c b/arch/arm64/kvm/context.c
> index 320afc6..acb4b1e 100644
> --- a/arch/arm64/kvm/context.c
> +++ b/arch/arm64/kvm/context.c
> @@ -25,10 +25,25 @@
>  void kvm_arm_setup_shadow_state(struct kvm_vcpu *vcpu)
>  {
>  	struct kvm_cpu_context *ctxt = &vcpu->arch.ctxt;
> +	if (unlikely(vcpu_mode_el2(vcpu))) {
> +		ctxt->hw_pstate = *vcpu_cpsr(vcpu) & ~PSR_MODE_MASK;
>  
> -	ctxt->hw_pstate = *vcpu_cpsr(vcpu);
> -	ctxt->hw_sys_regs = ctxt->sys_regs;
> -	ctxt->hw_sp_el1 = ctxt->gp_regs.sp_el1;
> +		/*
> +		 * We emulate virtual EL2 mode in hardware EL1 mode using the
> +		 * same stack pointer mode as the guest expects.
> +		 */

I think this comment should either be deleted or explain why this works
as opposed to stating the obvious.  How about:

		/*
		 * We can emulate the guest's configuration of which
		 * stack pointer to use when executing in virtual EL2 by
		 * using the equivalent feature in EL1 to point to
		 * either the EL1 or EL0 stack pointer.
		 */

> +		if ((*vcpu_cpsr(vcpu) & PSR_MODE_MASK) == PSR_MODE_EL2h)
> +			ctxt->hw_pstate |= PSR_MODE_EL1h;
> +		else
> +			ctxt->hw_pstate |= PSR_MODE_EL1t;
> +
> +		ctxt->hw_sys_regs = ctxt->shadow_sys_regs;
> +		ctxt->hw_sp_el1 = ctxt->el2_regs[SP_EL2];
> +	} else {
> +		ctxt->hw_pstate = *vcpu_cpsr(vcpu);
> +		ctxt->hw_sys_regs = ctxt->sys_regs;
> +		ctxt->hw_sp_el1 = ctxt->gp_regs.sp_el1;
> +	}
>  }
>  
>  /**
> @@ -38,9 +53,14 @@ void kvm_arm_setup_shadow_state(struct kvm_vcpu *vcpu)
>  void kvm_arm_restore_shadow_state(struct kvm_vcpu *vcpu)
>  {
>  	struct kvm_cpu_context *ctxt = &vcpu->arch.ctxt;
> -
> -	*vcpu_cpsr(vcpu) = ctxt->hw_pstate;
> -	ctxt->gp_regs.sp_el1 = ctxt->hw_sp_el1;
> +	if (unlikely(vcpu_mode_el2(vcpu))) {
> +		*vcpu_cpsr(vcpu) &= PSR_MODE_MASK;
> +		*vcpu_cpsr(vcpu) |= ctxt->hw_pstate & ~PSR_MODE_MASK;
> +		ctxt->el2_regs[SP_EL2] = ctxt->hw_sp_el1;
> +	} else {
> +		*vcpu_cpsr(vcpu) = ctxt->hw_pstate;
> +		ctxt->gp_regs.sp_el1 = ctxt->hw_sp_el1;
> +	}
>  }
>  
>  void kvm_arm_init_cpu_context(kvm_cpu_context_t *cpu_ctxt)
> -- 
> 1.9.1
> 
>

Back to linux.kernel | Previous | Next | Find similar | Unroll thread

Thread

Re: [RFC 08/55] KVM: arm64: Set virtual EL2 context depending on the  guest exception level Christoffer Dall <cdall@linaro.org> - 2017-02-22 12:20 +0100

csiph-web