Hi Sergej, On 06/27/2017 12:52 PM, Sergej Proskurin wrote:
The function p2m_mem_access_check_and_get_page in mem_access.c translates a gva to an ipa by means of the hardware functionality of the ARM architecture. This is implemented in the function gva_to_ipa. If mem_access is active, hardware-based gva to ipa translation might fail, as gva_to_ipa uses the guest's translation tables, access to which might be restricted by the active VTTBR. To address this issue, in this commit we add a software-based guest-page-table walk, which will be used by the function p2m_mem_access_check_and_get_page perform the gva to ipa translation in software in one of the following commits.Note: The introduced function guest_walk_tables assumes that the domain, the gva of which is to be translated, is running on the currently active vCPU. To walk the guest's page tables on a different vCPU, the following registers would need to be loaded: TCR_EL1, TTBR0_EL1, TTBR1_EL1, and SCTLR_EL1. Signed-off-by: Sergej Proskurin <prosku...@sec.in.tum.de> Acked-by: Julien Grall <julien.gr...@arm.com> --- Cc: Stefano Stabellini <sstabell...@kernel.org> Cc: Julien Grall <julien.gr...@arm.com> --- v2: Rename p2m_gva_to_ipa to p2m_walk_gpt and move it to p2m.c. Move the functionality responsible for walking long-descriptor based translation tables out of the function p2m_walk_gpt. Also move out the long-descriptor based translation out of this commit. Change function parameters in order to return access access rights to a requested gva. Cosmetic fixes. v3: Rename the introduced functions to guest_walk_(tables|sd|ld) and move the implementation to guest_copy.(c|h). Set permissions in guest_walk_tables also if the MMU is disabled. Change the function parameter of type "struct p2m_domain *" to "struct vcpu *" in the function guest_walk_tables. v4: Change the function parameter of type "struct p2m_domain *" to "struct vcpu *" in the functions guest_walk_(sd|ld) as well. v5: Merge two if-statements in guest_walk_tables to ease readability. Set perms to GV2M_READ as to avoid undefined permissions.
I would appreciate if you mention that you kept my tag even with the change made and asked whether I am happy with it...
In this case, you need a bit more rationale to explain why setting to GV2M_READ by default is fine... If it is just a random value, then say it.
Cheers. -- Julien Grall _______________________________________________ Xen-devel mailing list Xen-devel@lists.xen.org https://lists.xen.org/xen-devel
