linux-kernel - Re: [PATCH v4 07/10] KVM: selftests: Support multiple vCPUs in demand paging test

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Message-ID: <20200127083946.wxdmo2sfauns75j6@kamzik.brq.redhat.com>
Date:   Mon, 27 Jan 2020 09:39:46 +0100
From:   Andrew Jones <drjones@...hat.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Ben Gardon <bgardon@...gle.com>, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, linux-kselftest@...r.kernel.org,
        Cannon Matthews <cannonmatthews@...gle.com>,
        Peter Xu <peterx@...hat.com>, Peter Shier <pshier@...gle.com>,
        Oliver Upton <oupton@...gle.com>
Subject: Re: [PATCH v4 07/10] KVM: selftests: Support multiple vCPUs in
 demand paging test

On Sat, Jan 25, 2020 at 10:39:20AM +0100, Paolo Bonzini wrote:
> On 24/01/20 11:49, Andrew Jones wrote:
> >> +
> >> +	/*
> >> +	 * Reserve twice the ammount of memory needed to map the test region and
> >> +	 * the page table / stacks region, at 4k, for page tables. Do the
> >> +	 * calculation with 4K page size: the smallest of all archs. (e.g., 64K
> >> +	 * page size guest will need even less memory for page tables).
> >> +	 */
> >> +	pages += (2 * pages) / PTES_PER_4K_PT;
> >> +	pages += ((2 * vcpus * vcpu_memory_bytes) >> PAGE_SHIFT_4K) /
> >> +		 PTES_PER_4K_PT;
> > pages needs to be rounded up to the next multiple of 16 in order for this
> > to work on aarch64 machines with 64k pages.
> 
> I think this is best done with a generic function that does the rounding
> and an arch-specific function that returns the page size.  Can you send
> a patch to implement this?
>

Sure. Will do.

Thanks,
drew