diff mbox series

[v3,2/2] KVM: s390: fix for hugepage vmalloc

Message ID 20210610154220.529122-3-imbrenda@linux.ibm.com (mailing list archive)
State New
Headers show
Series mm: add vmalloc_no_huge and use it | expand

Commit Message

Claudio Imbrenda June 10, 2021, 3:42 p.m. UTC
The Create Secure Configuration Ultravisor Call does not support using
large pages for the virtual memory area. This is a hardware limitation.

This patch replaces the vzalloc call with an almost equivalent call to
the newly introduced vmalloc_no_huge function, which guarantees that
only small pages will be used for the backing.

The new call will not clear the allocated memory, but that has never
been an actual requirement.

Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Christoph Hellwig <hch@infradead.org>
---
 arch/s390/kvm/pv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Comments

Christian Borntraeger June 10, 2021, 3:56 p.m. UTC | #1
On 10.06.21 17:42, Claudio Imbrenda wrote:
> The Create Secure Configuration Ultravisor Call does not support using
> large pages for the virtual memory area. This is a hardware limitation.
> 
> This patch replaces the vzalloc call with an almost equivalent call to
> the newly introduced vmalloc_no_huge function, which guarantees that
> only small pages will be used for the backing.
> 
> The new call will not clear the allocated memory, but that has never
> been an actual requirement.
> 
> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Nicholas Piggin <npiggin@gmail.com>
> Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: David Rientjes <rientjes@google.com>
> Cc: Christoph Hellwig <hch@infradead.org>
> ---
>   arch/s390/kvm/pv.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
> index 813b6e93dc83..ad7c6d7cc90b 100644
> --- a/arch/s390/kvm/pv.c
> +++ b/arch/s390/kvm/pv.c
> @@ -140,7 +140,7 @@ static int kvm_s390_pv_alloc_vm(struct kvm *kvm)
>   	/* Allocate variable storage */
>   	vlen = ALIGN(virt * ((npages * PAGE_SIZE) / HPAGE_SIZE), PAGE_SIZE);
>   	vlen += uv_info.guest_virt_base_stor_len;
> -	kvm->arch.pv.stor_var = vzalloc(vlen);
> +	kvm->arch.pv.stor_var = vmalloc_no_huge(vlen);

dont we need a memset now?

>   	if (!kvm->arch.pv.stor_var)
>   		goto out_err;
>   	return 0;
>
Nicholas Piggin June 14, 2021, 1:43 a.m. UTC | #2
Sorry, catching up with email, I should have replied here originally.

Excerpts from Claudio Imbrenda's message of June 11, 2021 1:42 am:
> The Create Secure Configuration Ultravisor Call does not support using
> large pages for the virtual memory area. This is a hardware limitation.
> 
> This patch replaces the vzalloc call with an almost equivalent call to
> the newly introduced vmalloc_no_huge function, which guarantees that
> only small pages will be used for the backing.
> 
> The new call will not clear the allocated memory, but that has never
> been an actual requirement.

Since it seems like you will submit another version, I think it would
make things clear to change "fix" to "prepare", which should avoid
misleading the reader and tripping up automatic backporting things.

You could also add the first paragraph as a comment in the code?

Otherwise it looks good to me.

Acked-by: Nicholas Piggin <npiggin@gmail.com>

> 
> Signed-off-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> Reviewed-by: Janosch Frank <frankja@linux.ibm.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Nicholas Piggin <npiggin@gmail.com>
> Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: David Rientjes <rientjes@google.com>
> Cc: Christoph Hellwig <hch@infradead.org>
> ---
>  arch/s390/kvm/pv.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
> index 813b6e93dc83..ad7c6d7cc90b 100644
> --- a/arch/s390/kvm/pv.c
> +++ b/arch/s390/kvm/pv.c
> @@ -140,7 +140,7 @@ static int kvm_s390_pv_alloc_vm(struct kvm *kvm)
>  	/* Allocate variable storage */
>  	vlen = ALIGN(virt * ((npages * PAGE_SIZE) / HPAGE_SIZE), PAGE_SIZE);
>  	vlen += uv_info.guest_virt_base_stor_len;
> -	kvm->arch.pv.stor_var = vzalloc(vlen);
> +	kvm->arch.pv.stor_var = vmalloc_no_huge(vlen);
>  	if (!kvm->arch.pv.stor_var)
>  		goto out_err;
>  	return 0;
> -- 
> 2.31.1
> 
>
diff mbox series

Patch

diff --git a/arch/s390/kvm/pv.c b/arch/s390/kvm/pv.c
index 813b6e93dc83..ad7c6d7cc90b 100644
--- a/arch/s390/kvm/pv.c
+++ b/arch/s390/kvm/pv.c
@@ -140,7 +140,7 @@  static int kvm_s390_pv_alloc_vm(struct kvm *kvm)
 	/* Allocate variable storage */
 	vlen = ALIGN(virt * ((npages * PAGE_SIZE) / HPAGE_SIZE), PAGE_SIZE);
 	vlen += uv_info.guest_virt_base_stor_len;
-	kvm->arch.pv.stor_var = vzalloc(vlen);
+	kvm->arch.pv.stor_var = vmalloc_no_huge(vlen);
 	if (!kvm->arch.pv.stor_var)
 		goto out_err;
 	return 0;