linux-kernel - Re: [PATCH v4 19/19] KVM: selftests: Add test for KVM_SET_USER_MEMORY

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Date:   Wed, 18 Dec 2019 08:39:59 -0800
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Christian Borntraeger <borntraeger@...ibm.com>
Cc:     James Hogan <jhogan@...nel.org>,
        Paul Mackerras <paulus@...abs.org>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Marc Zyngier <maz@...nel.org>,
        David Hildenbrand <david@...hat.com>,
        Cornelia Huck <cohuck@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        James Morse <james.morse@....com>,
        Julien Thierry <julien.thierry.kdev@...il.com>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        linux-mips@...r.kernel.org, kvm-ppc@...r.kernel.org,
        kvm@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        kvmarm@...ts.cs.columbia.edu, linux-kernel@...r.kernel.org,
        Christoffer Dall <christoffer.dall@....com>,
        Philippe Mathieu-Daudé <f4bug@...at.org>
Subject: Re: [PATCH v4 19/19] KVM: selftests: Add test for
 KVM_SET_USER_MEMORY_REGION

On Wed, Dec 18, 2019 at 12:39:43PM +0100, Christian Borntraeger wrote:
> 
> On 17.12.19 21:40, Sean Christopherson wrote:
> > Add a KVM selftest to test moving the base gfn of a userspace memory
> > region.  The test is primarily targeted at x86 to verify its memslot
> > metadata is correctly updated, but also provides basic functionality
> > coverage on other architectures.
> > +static void *vcpu_worker(void *data)
> > +{
> > +	struct kvm_vm *vm = data;
> > +	struct kvm_run *run;
> > +	struct ucall uc;
> > +	uint64_t cmd;
> > +
> > +	/*
> > +	 * Loop until the guest is done.  Re-enter the guest on all MMIO exits,
> > +	 * which will occur if the guest attempts to access a memslot while it
> > +	 * is being moved.
> > +	 */
> > +	run = vcpu_state(vm, VCPU_ID);
> > +	do {
> > +		vcpu_run(vm, VCPU_ID);
> > +	} while (run->exit_reason == KVM_EXIT_MMIO);
> > +
> > +	TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
> > +		    "Unexpected exit reason = %d", run->exit_reason);
> 
> 
> This will also not work for s390. Maybe just make this test x86 specific for now?

Doh, that's obvious in hindsight.  I think the basic premise is also
broken on arm64 as it returns -EFAULT on is_error_noslot_pfn(pfn).  So
yeah, x86 only for now :-(