Subject: Re: [PATCH v4 09/66] KVM: arm64: nv: Support virtual EL2 exceptions

From: Marc Zyngier <[email-masked]>
Date: Mon, 24 May 2021 13:35:24 +0100

On Thu, 20 May 2021 13:55:48 +0100,
Zenghui Yu <[email-masked]> wrote:
> 
> On 2021/5/11 0:58, Marc Zyngier wrote:
> > From: Jintack Lim <[email-masked]>
> > 
> > Support injecting exceptions and performing exception returns to and
> > from virtual EL2.  This must be done entirely in software except when
> > taking an exception from vEL0 to vEL2 when the virtual HCR_EL2.{E2H,TGE}
> > == {1,1}  (a VHE guest hypervisor).
> > 
> > Signed-off-by: Jintack Lim <[email-masked]>
> > Signed-off-by: Christoffer Dall <[email-masked]>
> > [maz: switch to common exception injection framework]
> > Signed-off-by: Marc Zyngier <[email-masked]>
> > ---
> >  arch/arm64/include/asm/kvm_arm.h     |  17 +++
> >  arch/arm64/include/asm/kvm_emulate.h |  10 ++
> >  arch/arm64/kvm/Makefile              |   2 +-
> >  arch/arm64/kvm/emulate-nested.c      | 176 +++++++++++++++++++++++++++
> >  arch/arm64/kvm/hyp/exception.c       |  45 +++++--
> >  arch/arm64/kvm/inject_fault.c        |  63 ++++++++--
> >  arch/arm64/kvm/trace_arm.h           |  59 +++++++++
> >  7 files changed, 354 insertions(+), 18 deletions(-)
> >  create mode 100644 arch/arm64/kvm/emulate-nested.c
> 
> [...]
> 
> >  static void inject_abt64(struct kvm_vcpu *vcpu, bool is_iabt, unsigned long addr)
> >  {
> >  	unsigned long cpsr = *vcpu_cpsr(vcpu);
> >  	bool is_aarch32 = vcpu_mode_is_32bit(vcpu);
> >  	u32 esr = 0;
> >  -	vcpu->arch.flags |= (KVM_ARM64_EXCEPT_AA64_EL1		|
> > -			     KVM_ARM64_EXCEPT_AA64_ELx_SYNC	|
> > -			     KVM_ARM64_PENDING_EXCEPTION);
> > -
> > -	vcpu_write_sys_reg(vcpu, addr, FAR_EL1);
> > +	pend_sync_exception(vcpu);
> >   	/*
> >  	 * Build an {i,d}abort, depending on the level and the
> > @@ -45,16 +79,22 @@ static void inject_abt64(struct kvm_vcpu *vcpu, bool is_iabt, unsigned long addr
> >  	if (!is_iabt)
> >  		esr |= ESR_ELx_EC_DABT_LOW << ESR_ELx_EC_SHIFT;
> >  -	vcpu_write_sys_reg(vcpu, esr | ESR_ELx_FSC_EXTABT, ESR_EL1);
> > +	esr |= ESR_ELx_FSC_EXTABT;
> > +
> > +	if (vcpu->arch.flags & KVM_ARM64_EXCEPT_AA64_EL1) {
> 
> This isn't the right way to pick between EL1 and EL2 since
> KVM_ARM64_EXCEPT_AA64_EL1 is (0 << 11), we will not be able
> to inject abort to EL1 that way.

Indeed, well observed. I'm squashing the following fix in this patch.

Thanks,

	M.

diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
index 27397ecf9a23..fe781557e42c 100644
--- a/arch/arm64/include/asm/kvm_host.h
+++ b/arch/arm64/include/asm/kvm_host.h
@@ -524,6 +524,7 @@ struct kvm_vcpu_arch {
 #define KVM_ARM64_EXCEPT_AA64_ELx_SERR	(3 << 9)
 #define KVM_ARM64_EXCEPT_AA64_EL1	(0 << 11)
 #define KVM_ARM64_EXCEPT_AA64_EL2	(1 << 11)
+#define KVM_ARM64_EXCEPT_AA64_EL_MASK	(1 << 11)
 
 /*
  * Overlaps with KVM_ARM64_EXCEPT_MASK on purpose so that it can't be
diff --git a/arch/arm64/kvm/inject_fault.c b/arch/arm64/kvm/inject_fault.c
index 06df0bb848ca..5dcf3f8b08b8 100644
--- a/arch/arm64/kvm/inject_fault.c
+++ b/arch/arm64/kvm/inject_fault.c
@@ -52,6 +52,11 @@ static void pend_sync_exception(struct kvm_vcpu *vcpu)
 	}
 }
 
+static bool match_target_el(struct kvm_vcpu *vcpu, unsigned long target)
+{
+	return (vcpu->arch.flags & KVM_ARM64_EXCEPT_AA64_EL_MASK) == target;
+}
+
 static void inject_abt64(struct kvm_vcpu *vcpu, bool is_iabt, unsigned long addr)
 {
 	unsigned long cpsr = *vcpu_cpsr(vcpu);
@@ -81,7 +86,7 @@ static void inject_abt64(struct kvm_vcpu *vcpu, bool is_iabt, unsigned long addr
 
 	esr |= ESR_ELx_FSC_EXTABT;
 
-	if (vcpu->arch.flags & KVM_ARM64_EXCEPT_AA64_EL1) {
+	if (match_target_el(vcpu, KVM_ARM64_EXCEPT_AA64_EL1)) {
 		vcpu_write_sys_reg(vcpu, addr, FAR_EL1);
 		vcpu_write_sys_reg(vcpu, esr, ESR_EL1);
 	} else {
@@ -103,7 +108,7 @@ static void inject_undef64(struct kvm_vcpu *vcpu)
 	if (kvm_vcpu_trap_il_is32bit(vcpu))
 		esr |= ESR_ELx_IL;
 
-	if (vcpu->arch.flags & KVM_ARM64_EXCEPT_AA64_EL1)
+	if (match_target_el(vcpu, KVM_ARM64_EXCEPT_AA64_EL1))
 		vcpu_write_sys_reg(vcpu, esr, ESR_EL1);
 	else
 		vcpu_write_sys_reg(vcpu, esr, ESR_EL2);

-- 
Without deviation from the norm, progress is not possible.

_______________________________________________
linux-arm-kernel mailing list
[email-masked]
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel