Subject: Re: [PATCH v7 5/7] kvmppc: Radix changes for secure guest

From: Sukadev Bhattiprolu <[email-masked]>
Date: Wed, 28 Aug 2019 20:05:52 -0700

> - After the guest becomes secure, when we handle a page fault of a page
>   belonging to SVM in HV, send that page to UV via UV_PAGE_IN.
> - Whenever a page is unmapped on the HV side, inform UV via UV_PAGE_INVAL.
> - Ensure all those routines that walk the secondary page tables of
>   the guest don't do so in case of secure VM. For secure guest, the
>   active secondary page tables are in secure memory and the secondary
>   page tables in HV are freed when guest becomes secure.
> 
> Signed-off-by: Bharata B Rao <[email-masked]>
> ---
>  arch/powerpc/include/asm/kvm_host.h       | 12 ++++++++++++
>  arch/powerpc/include/asm/ultravisor-api.h |  1 +
>  arch/powerpc/include/asm/ultravisor.h     |  5 +++++
>  arch/powerpc/kvm/book3s_64_mmu_radix.c    | 22 ++++++++++++++++++++++
>  arch/powerpc/kvm/book3s_hv_devm.c         | 20 ++++++++++++++++++++
>  5 files changed, 60 insertions(+)
> 
> diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
> index 66e5cc8c9759..29333e8de1c4 100644
> --- a/arch/powerpc/include/asm/kvm_host.h
> +++ b/arch/powerpc/include/asm/kvm_host.h
> @@ -867,6 +867,8 @@ static inline void kvm_arch_vcpu_block_finish(struct kvm_vcpu *vcpu) {}
>  #ifdef CONFIG_PPC_UV
>  extern int kvmppc_devm_init(void);
>  extern void kvmppc_devm_free(void);
> +extern bool kvmppc_is_guest_secure(struct kvm *kvm);
> +extern int kvmppc_send_page_to_uv(struct kvm *kvm, unsigned long gpa);
>  #else
>  static inline int kvmppc_devm_init(void)
>  {
> @@ -874,6 +876,16 @@ static inline int kvmppc_devm_init(void)
>  }
> 
>  static inline void kvmppc_devm_free(void) {}
> +
> +static inline bool kvmppc_is_guest_secure(struct kvm *kvm)
> +{
> +	return false;
> +}
> +
> +static inline int kvmppc_send_page_to_uv(struct kvm *kvm, unsigned long gpa)
> +{
> +	return -EFAULT;
> +}
>  #endif /* CONFIG_PPC_UV */
> 
>  #endif /* __POWERPC_KVM_HOST_H__ */
> diff --git a/arch/powerpc/include/asm/ultravisor-api.h b/arch/powerpc/include/asm/ultravisor-api.h
> index 46b1ee381695..cf200d4ce703 100644
> --- a/arch/powerpc/include/asm/ultravisor-api.h
> +++ b/arch/powerpc/include/asm/ultravisor-api.h
> @@ -29,5 +29,6 @@
>  #define UV_UNREGISTER_MEM_SLOT		0xF124
>  #define UV_PAGE_IN			0xF128
>  #define UV_PAGE_OUT			0xF12C
> +#define UV_PAGE_INVAL			0xF138
> 
>  #endif /* _ASM_POWERPC_ULTRAVISOR_API_H */
> diff --git a/arch/powerpc/include/asm/ultravisor.h b/arch/powerpc/include/asm/ultravisor.h
> index 719c0c3930b9..b333241bbe4c 100644
> --- a/arch/powerpc/include/asm/ultravisor.h
> +++ b/arch/powerpc/include/asm/ultravisor.h
> @@ -57,4 +57,9 @@ static inline int uv_unregister_mem_slot(u64 lpid, u64 slotid)
>  	return ucall_norets(UV_UNREGISTER_MEM_SLOT, lpid, slotid);
>  }
> 
> +static inline int uv_page_inval(u64 lpid, u64 gpa, u64 page_shift)
> +{
> +	return ucall_norets(UV_PAGE_INVAL, lpid, gpa, page_shift);
> +}
> +
>  #endif	/* _ASM_POWERPC_ULTRAVISOR_H */
> diff --git a/arch/powerpc/kvm/book3s_64_mmu_radix.c b/arch/powerpc/kvm/book3s_64_mmu_radix.c
> index 2d415c36a61d..93ad34e63045 100644
> --- a/arch/powerpc/kvm/book3s_64_mmu_radix.c
> +++ b/arch/powerpc/kvm/book3s_64_mmu_radix.c
> @@ -19,6 +19,8 @@
>  #include <asm/pgtable.h>
>  #include <asm/pgalloc.h>
>  #include <asm/pte-walk.h>
> +#include <asm/ultravisor.h>
> +#include <asm/kvm_host.h>
> 
>  /*
>   * Supported radix tree geometry.
> @@ -915,6 +917,9 @@ int kvmppc_book3s_radix_page_fault(struct kvm_run *run, struct kvm_vcpu *vcpu,
>  	if (!(dsisr & DSISR_PRTABLE_FAULT))
>  		gpa |= ea & 0xfff;
> 
> +	if (kvmppc_is_guest_secure(kvm))
> +		return kvmppc_send_page_to_uv(kvm, gpa & PAGE_MASK);
> +
>  	/* Get the corresponding memslot */
>  	memslot = gfn_to_memslot(kvm, gfn);
> 
> @@ -972,6 +977,11 @@ int kvm_unmap_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
>  	unsigned long gpa = gfn << PAGE_SHIFT;
>  	unsigned int shift;
> 
> +	if (kvmppc_is_guest_secure(kvm)) {
> +		uv_page_inval(kvm->arch.lpid, gpa, PAGE_SIZE);
> +		return 0;
> +	}

If it is a page we share with UV, won't we need to drop the HV mapping
for the page?
> +
>  	ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
>  	if (ptep && pte_present(*ptep))
>  		kvmppc_unmap_pte(kvm, ptep, gpa, shift, memslot,
> @@ -989,6 +999,9 @@ int kvm_age_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
>  	int ref = 0;
>  	unsigned long old, *rmapp;
> 
> +	if (kvmppc_is_guest_secure(kvm))
> +		return ref;
> +
>  	ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
>  	if (ptep && pte_present(*ptep) && pte_young(*ptep)) {
>  		old = kvmppc_radix_update_pte(kvm, ptep, _PAGE_ACCESSED, 0,
> @@ -1013,6 +1026,9 @@ int kvm_test_age_radix(struct kvm *kvm, struct kvm_memory_slot *memslot,
>  	unsigned int shift;
>  	int ref = 0;
> 
> +	if (kvmppc_is_guest_secure(kvm))
> +		return ref;
> +
>  	ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
>  	if (ptep && pte_present(*ptep) && pte_young(*ptep))
>  		ref = 1;
> @@ -1030,6 +1046,9 @@ static int kvm_radix_test_clear_dirty(struct kvm *kvm,
>  	int ret = 0;
>  	unsigned long old, *rmapp;
> 
> +	if (kvmppc_is_guest_secure(kvm))
> +		return ret;
> +
>  	ptep = __find_linux_pte(kvm->arch.pgtable, gpa, NULL, &shift);
>  	if (ptep && pte_present(*ptep) && pte_dirty(*ptep)) {
>  		ret = 1;
> @@ -1082,6 +1101,9 @@ void kvmppc_radix_flush_memslot(struct kvm *kvm,
>  	unsigned long gpa;
>  	unsigned int shift;
> 
> +	if (kvmppc_is_guest_secure(kvm))
> +		return;
> +
>  	gpa = memslot->base_gfn << PAGE_SHIFT;
>  	spin_lock(&kvm->mmu_lock);
>  	for (n = memslot->npages; n; --n) {
> diff --git a/arch/powerpc/kvm/book3s_hv_devm.c b/arch/powerpc/kvm/book3s_hv_devm.c
> index 494495806407..19cfad340a51 100644
> --- a/arch/powerpc/kvm/book3s_hv_devm.c
> +++ b/arch/powerpc/kvm/book3s_hv_devm.c
> @@ -49,6 +49,11 @@ struct kvmppc_devm_page_pvt {
>  	bool skip_page_out;
>  };
> 
> +bool kvmppc_is_guest_secure(struct kvm *kvm)
> +{
> +	return !!(kvm->arch.secure_guest & KVMPPC_SECURE_INIT_DONE);
> +}
> +
>  unsigned long kvmppc_h_svm_init_start(struct kvm *kvm)
>  {
>  	struct kvm_memslots *slots;
> @@ -453,6 +458,21 @@ kvmppc_h_svm_page_out(struct kvm *kvm, unsigned long gpa,
>  	return ret;
>  }
> 
> +int kvmppc_send_page_to_uv(struct kvm *kvm, unsigned long gpa)
> +{
> +	unsigned long pfn;
> +	int ret;
> +
> +	pfn = gfn_to_pfn(kvm, gpa >> PAGE_SHIFT);
> +	if (is_error_noslot_pfn(pfn))
> +		return -EFAULT;
> +
> +	ret = uv_page_in(kvm->arch.lpid, pfn << PAGE_SHIFT, gpa, 0, PAGE_SHIFT);
> +	kvm_release_pfn_clean(pfn);
> +
> +	return (ret == U_SUCCESS) ? RESUME_GUEST : -EFAULT;
> +}
> +
>  static u64 kvmppc_get_secmem_size(void)
>  {
>  	struct device_node *np;
> -- 
> 2.21.0