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Date:   Thu, 21 Oct 2021 17:26:26 +0200
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Subject: Re: [RFC 03/16] KVM: selftests: handle encryption bits in page tables
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To:     Michael Roth <michael.roth@amd.com>,
        linux-kselftest@vger.kernel.org
Cc:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org,
        Nathan Tempelman <natet@google.com>,
        Marc Orr <marcorr@google.com>,
        Steve Rutherford <srutherford@google.com>,
        Sean Christopherson <seanjc@google.com>,
        Mingwei Zhang <mizhang@google.com>,
        Brijesh Singh <brijesh.singh@amd.com>,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Varad Gautam <varad.gautam@suse.com>,
        Shuah Khan <shuah@kernel.org>,
        Vitaly Kuznetsov <vkuznets@redhat.com>,
        David Woodhouse <dwmw@amazon.co.uk>,
        Ricardo Koller <ricarkol@google.com>,
        Jim Mattson <jmattson@google.com>,
        Wanpeng Li <wanpengli@tencent.com>,
        Joerg Roedel <joro@8bytes.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        "H . Peter Anvin" <hpa@zytor.com>
References: <20211005234459.430873-1-michael.roth@amd.com>
 <20211005234459.430873-4-michael.roth@amd.com>
From:   Paolo Bonzini <pbonzini@redhat.com>
In-Reply-To: <20211005234459.430873-4-michael.roth@amd.com>
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On 06/10/21 01:44, Michael Roth wrote:
> SEV guests rely on an encyption bit which resides within the range that
> current code treats as address bits. Guest code will expect these bits
> to be set appropriately in their page tables, whereas helpers like
> addr_gpa2hva() will expect these bits to be masked away prior to
> translation. Add proper handling for these cases.

This is not what you're doing below in addr_gpa2hva, though---or did I 
misunderstand?

I may be wrong due to not actually having written the code, but I'd 
prefer if most of these APIs worked only if the C bit has already been 
stripped.  In general it's quite unlikely for host code to deal with C=1 
pages, so it's worth pointing out explicitly the cases where it does.

Paolo

> @@ -1460,9 +1480,10 @@ void virt_map(struct kvm_vm *vm, uint64_t vaddr, uint64_t paddr,
>    * address providing the memory to the vm physical address is returned.
>    * A TEST_ASSERT failure occurs if no region containing gpa exists.
>    */
> -void *addr_gpa2hva(struct kvm_vm *vm, vm_paddr_t gpa)
> +void *addr_gpa2hva(struct kvm_vm *vm, vm_paddr_t gpa_raw)
>   {
>   	struct userspace_mem_region *region;