Re: [PATCH v9 2/5] arm64: KVM: encapsulate kvm_cpu_context in kvm_host_data

[Andrew Murray <andrew.murray@arm.com>]

On Thu, Jan 10, 2019 at 11:36:01AM +0000, Suzuki K Poulose wrote:
> Hi Andrew,
> 
> On 07/01/2019 14:41, Andrew Murray wrote:
> > The virt/arm core allocates a kvm_cpu_context_t percpu, at present this is
> > a typedef to kvm_cpu_context and is used to store host cpu context. The
> > kvm_cpu_context structure is also used elsewhere to hold vcpu context.
> > In order to use the percpu to hold additional future host information we
> > encapsulate kvm_cpu_context in a new structure and rename the typedef and
> > percpu to match.
> > 
> > Signed-off-by: Andrew Murray <andrew.murray@arm.com>
> > ---
> >   arch/arm/include/asm/kvm_host.h   |  8 ++++++--
> >   arch/arm64/include/asm/kvm_asm.h  |  4 ++--
> >   arch/arm64/include/asm/kvm_host.h | 14 +++++++++-----
> >   arch/arm64/kernel/asm-offsets.c   |  2 +-
> >   virt/kvm/arm/arm.c                | 12 +++++++-----
> >   5 files changed, 25 insertions(+), 15 deletions(-)
> > 
> > diff --git a/arch/arm/include/asm/kvm_host.h b/arch/arm/include/asm/kvm_host.h
> > index 79906ce..71645ba 100644
> > --- a/arch/arm/include/asm/kvm_host.h
> > +++ b/arch/arm/include/asm/kvm_host.h
> > @@ -145,7 +145,11 @@ struct kvm_cpu_context {
> >   	u32 cp15[NR_CP15_REGS];
> >   };
> > -typedef struct kvm_cpu_context kvm_cpu_context_t;
> > +struct kvm_host_data {
> > +	struct kvm_cpu_context host_ctxt;
> > +};
> > +
> > +typedef struct kvm_host_data kvm_host_data_t;
> >   struct kvm_vcpu_arch {
> >   	struct kvm_cpu_context ctxt;
> > @@ -163,7 +167,7 @@ struct kvm_vcpu_arch {
> >   	struct kvm_vcpu_fault_info fault;
> >   	/* Host FP context */
> > -	kvm_cpu_context_t *host_cpu_context;
> > +	struct kvm_cpu_context *host_cpu_context;
> >   	/* VGIC state */
> >   	struct vgic_cpu vgic_cpu;
> > diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
> > index 102b5a5..6a9bfd4 100644
> > --- a/arch/arm64/include/asm/kvm_asm.h
> > +++ b/arch/arm64/include/asm/kvm_asm.h
> > @@ -102,12 +102,12 @@ extern u32 __init_stage2_translation(void);
> >   .endm
> >   .macro get_host_ctxt reg, tmp
> > -	hyp_adr_this_cpu \reg, kvm_host_cpu_state, \tmp
> > +	hyp_adr_this_cpu \reg, kvm_host_data, \tmp
> >   .endm
> 
> minor nit: We now load "kvm_host_data" instead of the host_ctxt here,
> even though they both are same. Do we need to make this explicitly load
> the address of the host_ctxt member to make sure this doesn't break
> with future changes to the structure ?
> i.e,
> 	add	\reg, \reg, #HOST_DATA_CONTEXT
> 
> Otherwise,
> 
> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>

Thanks for spotting this.

Are you happy for me to add the Reviewed-by tag if I squash in the following?

diff --git a/arch/arm64/include/asm/kvm_asm.h b/arch/arm64/include/asm/kvm_asm.h
index 6a9bfd4..f182d13 100644
--- a/arch/arm64/include/asm/kvm_asm.h
+++ b/arch/arm64/include/asm/kvm_asm.h
@@ -103,11 +103,12 @@ extern u32 __init_stage2_translation(void);
 
 .macro get_host_ctxt reg, tmp
        hyp_adr_this_cpu \reg, kvm_host_data, \tmp
+       add     \reg, \reg, #HOST_DATA_CONTEXT
 .endm
 
 .macro get_vcpu_ptr vcpu, ctxt
        get_host_ctxt \ctxt, \vcpu
-       ldr     \vcpu, [\ctxt, #HOST_DATA_VCPU]
+       ldr     \vcpu, [\ctxt, #HOST_CONTEXT_VCPU]
        kern_hyp_va     \vcpu
 .endm
 
diff --git a/arch/arm64/kernel/asm-offsets.c b/arch/arm64/kernel/asm-offsets.c
index cb968ff..0deddfb 100644
--- a/arch/arm64/kernel/asm-offsets.c
+++ b/arch/arm64/kernel/asm-offsets.c
@@ -142,7 +142,8 @@ int main(void)
   DEFINE(CPU_FP_REGS,          offsetof(struct kvm_regs, fp_regs));
   DEFINE(VCPU_FPEXC32_EL2,     offsetof(struct kvm_vcpu, arch.ctxt.sys_regs[FPEXC32_EL2]));
   DEFINE(VCPU_HOST_CONTEXT,    offsetof(struct kvm_vcpu, arch.host_cpu_context));
-  DEFINE(HOST_DATA_VCPU,       offsetof(struct kvm_host_data, host_ctxt.__hyp_running_vcpu));
+  DEFINE(HOST_CONTEXT_VCPU,    offsetof(struct kvm_cpu_context, __hyp_running_vcpu));
+  DEFINE(HOST_DATA_CONTEXT,    offsetof(struct kvm_host_data, host_ctxt));
 #endif
 #ifdef CONFIG_CPU_PM
   DEFINE(CPU_SUSPEND_SZ,       sizeof(struct cpu_suspend_ctx));


Thanks,

Andrew Murray