linux-kernel - Re: [PATCH v13 098/113] KVM: TDX: Handle TDX PV map

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Message-ID: <20230418190904.1111011-1-vannapurve@google.com>
Date:   Tue, 18 Apr 2023 19:09:04 +0000
From:   Vishal Annapurve <vannapurve@...gle.com>
To:     isaku.yamahata@...el.com
Cc:     dmatlack@...gle.com, erdemaktas@...gle.com,
        isaku.yamahata@...il.com, kai.huang@...el.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, pbonzini@...hat.com,
        sagis@...gle.com, seanjc@...gle.com, zhi.wang.linux@...il.com
Subject: Re: [PATCH v13 098/113] KVM: TDX: Handle TDX PV map_gpa hypercall

> +static int tdx_map_gpa(struct kvm_vcpu *vcpu)
> +{
> +	struct kvm *kvm = vcpu->kvm;
> +	gpa_t gpa = tdvmcall_a0_read(vcpu);
> +	gpa_t size = tdvmcall_a1_read(vcpu);
> +	gpa_t end = gpa + size;
> +
> +	if (!IS_ALIGNED(gpa, PAGE_SIZE) || !IS_ALIGNED(size, PAGE_SIZE) ||
> +	    end < gpa ||
> +	    end > kvm_gfn_shared_mask(kvm) << (PAGE_SHIFT + 1) ||
> +	    kvm_is_private_gpa(kvm, gpa) != kvm_is_private_gpa(kvm, end)) {
> +		tdvmcall_set_return_code(vcpu, TDG_VP_VMCALL_INVALID_OPERAND);
> +		return 1;
> +	}
> +
> +	return tdx_vp_vmcall_to_user(vcpu);

This will result into exits to userspace for MMIO regions as well. Does it make
sense to only exit to userspace for guest physical memory regions backed by
memslots?

> +}
> +