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keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL In-Reply-To: <20260420093820.825969-2-julian.vetter@vates.tech> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-purgate-ID: tlsNG-16d1c6/1787058395-FD00977B-BF8C582F/0/0 X-purgate-type: clean X-purgate-size: 4645 On 20.04.2026 11:38, Julian Vetter wrote: > Switch the Xen-side ioreq page mapping from prepare_ring_for_helper() / > map_domain_page_global() to explicit vmap(), to ensure vmap_to_page() > can recover the struct page_info * uniformly during teardown. What's after the comma isn't really the main reason for this patch, is it? Describing this aspect ... > This is a prerequisite for multi-page ioreq support: the non-buf ioreq > region will need to span multiple pages for domains with more vCPUs than > fit in a single page, and vmap() is the natural interface for contiguous > multi-page Xen VA mappings. > > In non-debug builds map_domain_page_global() uses the directmap for low > MFNs rather than vmap(), so this change has a small overhead in the > common case. Debug builds already used vmap() indirectly. > > With both paths using vmap(), vmap_to_page() can recover the struct > page_info * uniformly, so drop the 'page' field from struct ioreq_page > and update all callers accordingly. ... here (at the bottom) is fully sufficient. > Signed-off-by: Julian Vetter > --- > Changes in v6: > - Updated commit message to clearly specify why these changes are made > - Added comment to say that this is {prepare,destroy}_ring_for_helper() > just using vmap_to_page() + v{map,unmap}() > - Kept proper ordering in ioreq_server_free_mfn(), first clearing the va > pointer before unmapping Yet then you didn't extend the same consideration ... > @@ -128,8 +129,13 @@ static void hvm_unmap_ioreq_gfn(struct ioreq_server *s, bool buf) > if ( gfn_eq(iorp->gfn, INVALID_GFN) ) > return; > > - destroy_ring_for_helper(&iorp->va, iorp->page); > - iorp->page = NULL; > + /* Equivalent to destroy_ring_for_helper(), using vmap_to_page(). */ > + if ( iorp->va ) > + { > + put_page_and_type(vmap_to_page(iorp->va)); > + vunmap(iorp->va); > + iorp->va = NULL; > + } ... to here. (Really we should perhaps introduce VUNMAP(), much like we have XFREE(), XVFREE(), etc.) Further the ordering doesn't match destroy_ring_for_helper(), which unmaps first and only then drops the page refs. > @@ -162,12 +171,40 @@ static int hvm_map_ioreq_gfn(struct ioreq_server *s, bool buf) > if ( gfn_eq(iorp->gfn, INVALID_GFN) ) > return -ENOMEM; > > - rc = prepare_ring_for_helper(d, gfn_x(iorp->gfn), &iorp->page, > - &iorp->va); > - > + /* > + * Equivalent to prepare_ring_for_helper() using vmap(). Using vmap() > + * rather than map_domain_page_global() ensures vmap_to_page() can > + * recover the struct page_info * uniformly at teardown, which is > + * needed to support multi-page ioreq mappings (see nr_ioreq_pages()). > + */ "is needed" is too strong, I think - surely there would be a way to handle that without vmap_to_page(), by tracking all struct page_info * separately. > @@ -309,15 +310,16 @@ static int ioreq_server_alloc_mfn(struct ioreq_server *s, bool buf) > static void ioreq_server_free_mfn(struct ioreq_server *s, bool buf) > { > struct ioreq_page *iorp = buf ? &s->bufioreq : &s->ioreq; > - struct page_info *page = iorp->page; > + struct page_info *page; > + void *va; > > - if ( !page ) > + if ( !iorp->va ) > return; > > - iorp->page = NULL; > - > - unmap_domain_page_global(iorp->va); > + va = iorp->va; Please can this be the initializer of the variable, for the if() above to then use that local var? > @@ -333,7 +335,8 @@ bool is_ioreq_server_page(struct domain *d, const struct page_info *page) > > FOR_EACH_IOREQ_SERVER(d, id, s) > { > - if ( (s->ioreq.page == page) || (s->bufioreq.page == page) ) > + if ( (s->ioreq.va && vmap_to_page(s->ioreq.va) == page) || > + (s->bufioreq.va && vmap_to_page(s->bufioreq.va) == page) ) > { > found = true; > break; You mention in the description that some extra overhead is introduced. The (generally) two page walks done here are particularly concerning. Since we have a valid struct page_info * available here, I wonder if we shouldn't aid this lookup by recording the VA in one of struct page_info's fields. Afaics vmap() doesn't use any of the fields, so it should be relatively easy to determine a field to use for this purpose. The more involved part would then be to make sure the field (in other struct page_info instances) is also properly different from any VA vmap() may return. Jan