| Message ID | 1483943091-1364-9-git-send-email-jintack@cs.columbia.edu |
|---|---|
| State | New |
| Headers | show |
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 > >
Jintack Lim <jintack@cs.columbia.edu> writes: > 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. > + */ > + if ((*vcpu_cpsr(vcpu) & PSR_MODE_MASK) == PSR_MODE_EL2h) > + ctxt->hw_pstate |= PSR_MODE_EL1h; > + else > + ctxt->hw_pstate |= PSR_MODE_EL1t; > + I see vcpu_mode(el2) does return mode == PSR_MODE_EL2h || mode == PSR_MODE_EL2t; I can't seem to find this, what's the difference between the modes: PSR_MODE_EL2h/EL2t ? Bandan > + 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)
On 01/06/17 21:22, Bandan Das wrote: > Jintack Lim <jintack@cs.columbia.edu> writes: > >> 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. >> + */ >> + if ((*vcpu_cpsr(vcpu) & PSR_MODE_MASK) == PSR_MODE_EL2h) >> + ctxt->hw_pstate |= PSR_MODE_EL1h; >> + else >> + ctxt->hw_pstate |= PSR_MODE_EL1t; >> + > > I see vcpu_mode(el2) does > return mode == PSR_MODE_EL2h || mode == PSR_MODE_EL2t; > > I can't seem to find this, what's the difference between > the modes: PSR_MODE_EL2h/EL2t ? The difference is the stack pointer that is getting used. When the CPU is at ELxh, it uses SPx at ELx. When at ELxt, it uses SP0 (the userspace stack pointer). See the definition of SPSR_EL2 in the ARMv8 ARM. Thanks, M. -- Jazz is not dead. It just smells funny...
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. + */ + 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)