[01/27] KVM: PPC: Introduce shared page

For transparent variable sharing between the hypervisor and guest, I introduce
a shared page. This shared page will contain all the registers the guest can
read and write safely without exiting guest context.

This patch only implements the stubs required for the basic structure of the
shared page. The actual register moving follows.

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 arch/powerpc/include/asm/kvm_host.h |    2 ++
 arch/powerpc/include/asm/kvm_para.h |    5 +++++
 arch/powerpc/kernel/asm-offsets.c   |    1 +
 arch/powerpc/kvm/44x.c              |    7 +++++++
 arch/powerpc/kvm/book3s.c           |    9 ++++++++-
 arch/powerpc/kvm/e500.c             |    7 +++++++
 6 files changed, 30 insertions(+), 1 deletions(-)

On 07/29/2010 05:47 AM, Alexander Graf wrote:
> For transparent variable sharing between the hypervisor and guest, I introduce
> a shared page. This shared page will contain all the registers the guest can
> read and write safely without exiting guest context.
>
> This patch only implements the stubs required for the basic structure of the
> shared page. The actual register moving follows.
>
> Signed-off-by: Alexander Graf<agraf@suse.de>
> ---
>   arch/powerpc/include/asm/kvm_host.h |    2 ++
>   arch/powerpc/include/asm/kvm_para.h |    5 +++++
>   arch/powerpc/kernel/asm-offsets.c   |    1 +
>   arch/powerpc/kvm/44x.c              |    7 +++++++
>   arch/powerpc/kvm/book3s.c           |    9 ++++++++-
>   arch/powerpc/kvm/e500.c             |    7 +++++++
>   6 files changed, 30 insertions(+), 1 deletions(-)
>
> diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
> index b0b23c0..53edacd 100644
> --- a/arch/powerpc/include/asm/kvm_host.h
> +++ b/arch/powerpc/include/asm/kvm_host.h
> @@ -25,6 +25,7 @@
>   #include<linux/interrupt.h>
>   #include<linux/types.h>
>   #include<linux/kvm_types.h>
> +#include<linux/kvm_para.h>
>   #include<asm/kvm_asm.h>
>
>   #define KVM_MAX_VCPUS 1
> @@ -290,6 +291,7 @@ struct kvm_vcpu_arch {
>   	struct tasklet_struct tasklet;
>   	u64 dec_jiffies;
>   	unsigned long pending_exceptions;
> +	struct kvm_vcpu_arch_shared *shared;
>
>   #ifdef CONFIG_PPC_BOOK3S
>   	struct hlist_head hpte_hash_pte[HPTEG_HASH_NUM_PTE];
> diff --git a/arch/powerpc/include/asm/kvm_para.h b/arch/powerpc/include/asm/kvm_para.h
> index 2d48f6a..1485ba8 100644
> --- a/arch/powerpc/include/asm/kvm_para.h
> +++ b/arch/powerpc/include/asm/kvm_para.h
> @@ -20,6 +20,11 @@
>   #ifndef __POWERPC_KVM_PARA_H__
>   #define __POWERPC_KVM_PARA_H__
>
> +#include<linux/types.h>
> +
> +struct kvm_vcpu_arch_shared {
> +};
> +
>   #ifdef __KERNEL__
>
>   static inline int kvm_para_available(void)
> diff --git a/arch/powerpc/kernel/asm-offsets.c b/arch/powerpc/kernel/asm-offsets.c
> index 496cc5b..944f593 100644
> --- a/arch/powerpc/kernel/asm-offsets.c
> +++ b/arch/powerpc/kernel/asm-offsets.c
> @@ -400,6 +400,7 @@ int main(void)
>   	DEFINE(VCPU_SPRG6, offsetof(struct kvm_vcpu, arch.sprg6));
>   	DEFINE(VCPU_SPRG7, offsetof(struct kvm_vcpu, arch.sprg7));
>   	DEFINE(VCPU_SHADOW_PID, offsetof(struct kvm_vcpu, arch.shadow_pid));
> +	DEFINE(VCPU_SHARED, offsetof(struct kvm_vcpu, arch.shared));
>
>   	/* book3s */
>   #ifdef CONFIG_PPC_BOOK3S
> diff --git a/arch/powerpc/kvm/44x.c b/arch/powerpc/kvm/44x.c
> index 73c0a3f..e7b1f3f 100644
> --- a/arch/powerpc/kvm/44x.c
> +++ b/arch/powerpc/kvm/44x.c
> @@ -123,8 +123,14 @@ struct kvm_vcpu *kvmppc_core_vcpu_create(struct kvm *kvm, unsigned int id)
>   	if (err)
>   		goto free_vcpu;
>
> +	vcpu->arch.shared = (void*)__get_free_page(GFP_KERNEL|__GFP_ZERO);
> +	if (!vcpu->arch.shared)
> +		goto uninit_vcpu;
> +
>   	return vcpu;
>
> +uninit_vcpu:
> +	kvm_vcpu_uninit(vcpu);
>   free_vcpu:
>   	kmem_cache_free(kvm_vcpu_cache, vcpu_44x);
>   out:
> @@ -135,6 +141,7 @@ void kvmppc_core_vcpu_free(struct kvm_vcpu *vcpu)
>   {
>   	struct kvmppc_vcpu_44x *vcpu_44x = to_44x(vcpu);
>
> +	free_page((unsigned long)vcpu->arch.shared);
>   	kvm_vcpu_uninit(vcpu);
>   	kmem_cache_free(kvm_vcpu_cache, vcpu_44x);
>   }
> diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c
> index a3cef30..b3385dd 100644
> --- a/arch/powerpc/kvm/book3s.c
> +++ b/arch/powerpc/kvm/book3s.c
> @@ -1242,6 +1242,10 @@ struct kvm_vcpu *kvmppc_core_vcpu_create(struct kvm *kvm, unsigned int id)
>   	if (err)
>   		goto free_shadow_vcpu;
>
> +	vcpu->arch.shared = (void*)__get_free_page(GFP_KERNEL|__GFP_ZERO);
> +	if (!vcpu->arch.shared)
> +		goto uninit_vcpu;
> +
>   	vcpu->arch.host_retip = kvm_return_point;
>   	vcpu->arch.host_msr = mfmsr();
>   #ifdef CONFIG_PPC_BOOK3S_64
> @@ -1268,10 +1272,12 @@ struct kvm_vcpu *kvmppc_core_vcpu_create(struct kvm *kvm, unsigned int id)
>
>   	err = kvmppc_mmu_init(vcpu);
>   	if (err<  0)
> -		goto free_shadow_vcpu;
> +		goto uninit_vcpu;
>
>   	return vcpu;
>
> +uninit_vcpu:
> +	kvm_vcpu_uninit(vcpu);
>   free_shadow_vcpu:
>   	kfree(vcpu_book3s->shadow_vcpu);
>   free_vcpu:
> @@ -1284,6 +1290,7 @@ void kvmppc_core_vcpu_free(struct kvm_vcpu *vcpu)
>   {
>   	struct kvmppc_vcpu_book3s *vcpu_book3s = to_book3s(vcpu);
>
> +	free_page((unsigned long)vcpu->arch.shared);
>   	kvm_vcpu_uninit(vcpu);
>   	kfree(vcpu_book3s->shadow_vcpu);
>   	vfree(vcpu_book3s);
> diff --git a/arch/powerpc/kvm/e500.c b/arch/powerpc/kvm/e500.c
> index e8a00b0..71750f2 100644
> --- a/arch/powerpc/kvm/e500.c
> +++ b/arch/powerpc/kvm/e500.c
> @@ -117,8 +117,14 @@ struct kvm_vcpu *kvmppc_core_vcpu_create(struct kvm *kvm, unsigned int id)
>   	if (err)
>   		goto uninit_vcpu;
>
> +	vcpu->arch.shared = (void*)__get_free_page(GFP_KERNEL|__GFP_ZERO);
> +	if (!vcpu->arch.shared)
> +		goto uninit_tlb;
> +
>   	return vcpu;
>
> +uninit_tlb:
> +	kvmppc_e500_tlb_uninit(vcpu_e500);
>   uninit_vcpu:
>   	kvm_vcpu_uninit(vcpu);
>   free_vcpu:
> @@ -131,6 +137,7 @@ void kvmppc_core_vcpu_free(struct kvm_vcpu *vcpu)
>   {
>   	struct kvmppc_vcpu_e500 *vcpu_e500 = to_e500(vcpu);
>
> +	free_page((unsigned long)vcpu->arch.shared);
>   	kvmppc_e500_tlb_uninit(vcpu_e500);
>   	kvm_vcpu_uninit(vcpu);
>   	kmem_cache_free(kvm_vcpu_cache, vcpu_e500);
>    
Why not put all this in a common function like kvm_arch_vcpu_init()? 
There are layers of shared code inside arch/powerpc/kvm: e.g. powerpc.c 
-> booke.c -> 44x.c...

Hollis Blanchard
Mentor Graphics, Embedded Systems Division