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

Christian Borntraeger
2021-06-10T15:57:16Z

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;
>