| Message ID | b19a5ca7abd27bd4f31a0d87573687297dd7df58.1719849287.git.alejandro.vallejo@cloud.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
| Series | [for-4.19?] xen/vmap: Document the vmap header | expand |
On 02.07.2024 15:03, Alejandro Vallejo wrote: > --- a/xen/include/xen/vmap.h > +++ b/xen/include/xen/vmap.h > @@ -1,34 +1,131 @@ > +/* > + * Interface to map physical memory onto contiguous virtual memory areas. > + * > + * Two ranges of linear address space are reserved for this purpose: A general > + * purpose area (VMAP_DEFAULT) and a livepatch-specific area (VMAP_XEN). The > + * latter is used when loading livepatches and the former for everything else. > + */ > #if !defined(__XEN_VMAP_H__) && defined(VMAP_VIRT_START) > #define __XEN_VMAP_H__ > > #include <xen/mm-frame.h> > #include <xen/page-size.h> > > +/** Identifiers for the linear ranges tracked by vmap */ Here and below: Why /** ? Seeing ... > enum vmap_region { > + /* > + * Region used for general purpose RW mappings. Mapping/allocating memory > + * here can induce extra allocations for the supporting page tables. > + */ ... this vs ... > VMAP_DEFAULT, > + /** > + * Region used for loading livepatches. Can't use VMAP_DEFAULT because it > + * must live close to the running Xen image. The caller also ensures all > + * page tables are already in place with adequate PTE flags. > + */ ... this, it's not even looking to be consistent. > VMAP_XEN, > + /** Sentinel value for bounds checking */ > VMAP_REGION_NR, > }; > > +/** > + * Runtime initialiser for each vmap region type > + * > + * Must only be called once per vmap region type. > + * > + * @param type Designation of the region to initialise. > + * @param start Start address of the `type` region. > + * @param end End address (not inclusive) of the `type` region > + */ > void vm_init_type(enum vmap_region type, void *start, void *end); > > +/** > + * Maps a range of physical ranges onto a single virtual range Largely related to it not really being clear what "a range of physical ranges" actually is, maybe "a set of physical ranges"? > + * `mfn` is an array of `nr` physical ranges, each of which is `granularity` > + * pages wide. `type` defines which vmap region to use for the mapping and > + * `flags` is the PTE flags the page table leaves are meant to have. > + * > + * Typically used via the vmap() and vmap_contig() helpers. > + * > + * @param mfn Array of mfns > + * @param granularity Number of contiguous pages each mfn represents > + * @param nr Number of mfns in the `mfn` array > + * @param align Alignment of the virtual area to map > + * @param flags PTE flags for the leaves of the PT tree. > + * @param type Which region to create the mappings on > + */ > void *__vmap(const mfn_t *mfn, unsigned int granularity, unsigned int nr, > unsigned int align, unsigned int flags, enum vmap_region type); > + > +/** > + * Map an arrray of pages contiguously into the VMAP_DEFAULT vmap region Nit: One r too many in "array". > + * @param[in] mfn Pointer to the base of an array of mfns > + * @param[in] nr Number of mfns in the array > + */ > void *vmap(const mfn_t *mfn, unsigned int nr); > + > +/** > + * Maps physically contiguous pages onto the VMAP_DEFAULT vmap region > + * > + * Used when the directmap is unavailable (i.e: due to secret hiding) Please omit this. There's no reason to suggest it can't also be used for other purposes. > + * @param mfn Base mfn of the physical region > + * @param nr Number of mfns in the physical region > + */ > void *vmap_contig(mfn_t mfn, unsigned int nr); > + > +/** > + * Unmaps a range of virtually contiguous memory from one of the vmap regions > + * > + * The system remembers internally how wide the mapping is and unmaps it all. > + * It also can determine the vmap region type from the `va`. > + * > + * @param va Virtual base address of the range to unmap > + */ > void vunmap(const void *va); > > +/** > + * Allocate `size` octets of possibly non-contiguous physical memory and map > + * them contiguously in the VMAP_DEFAULT vmap region > + * > + * The system remembers internally how wide the mapping is and unmaps it all. This is a verbatim copy of what you say for vunmap(), yet it looks unrelated here. Maybe you meant to edit it after copy-and-paste? Or maybe this was meant to go ... > + * @param size Pointer to the base of an array of mfns > + * @return Pointer to the mapped area on success; NULL otherwise. > + */ > void *vmalloc(size_t size); > + > +/** Same as vmalloc(), but for the VMAP_XEN vmap region. */ > void *vmalloc_xen(size_t size); > > +/** Same as vmalloc(), but set the contents to zero before returning */ > void *vzalloc(size_t size); > + > +/** > + * Unmap and free memory from vmalloc(), vmalloc_xen() or vzalloc() > + * > + * @param va Virtual base address of the range to free and unmap > + */ > void vfree(void *va); ... here? Also, if you want this to be considered for 4.19, please don't forget to Cc Oleksii. Jan
On Wed Jul 3, 2024 at 8:41 AM BST, Jan Beulich wrote: > On 02.07.2024 15:03, Alejandro Vallejo wrote: > > --- a/xen/include/xen/vmap.h > > +++ b/xen/include/xen/vmap.h > > @@ -1,34 +1,131 @@ > > +/* > > + * Interface to map physical memory onto contiguous virtual memory areas. > > + * > > + * Two ranges of linear address space are reserved for this purpose: A general > > + * purpose area (VMAP_DEFAULT) and a livepatch-specific area (VMAP_XEN). The > > + * latter is used when loading livepatches and the former for everything else. > > + */ > > #if !defined(__XEN_VMAP_H__) && defined(VMAP_VIRT_START) > > #define __XEN_VMAP_H__ > > > > #include <xen/mm-frame.h> > > #include <xen/page-size.h> > > > > +/** Identifiers for the linear ranges tracked by vmap */ > > Here and below: Why /** ? Seeing ... > > > enum vmap_region { > > + /* > > + * Region used for general purpose RW mappings. Mapping/allocating memory > > + * here can induce extra allocations for the supporting page tables. > > + */ > > ... this vs ... > > > VMAP_DEFAULT, > > + /** > > + * Region used for loading livepatches. Can't use VMAP_DEFAULT because it > > + * must live close to the running Xen image. The caller also ensures all > > + * page tables are already in place with adequate PTE flags. > > + */ > > ... this, it's not even looking to be consistent. > > > VMAP_XEN, > > + /** Sentinel value for bounds checking */ > > VMAP_REGION_NR, > > }; Double stars are Doxygen style for documenting interfaces. I don't mind getting rid of those. Some functions exhibit them in the arm port, but it's true virtually nothing in common Xen does. VMAP_XEN's comment was meant to have it too, I just missed it :) > > > > +/** > > + * Runtime initialiser for each vmap region type > > + * > > + * Must only be called once per vmap region type. > > + * > > + * @param type Designation of the region to initialise. > > + * @param start Start address of the `type` region. > > + * @param end End address (not inclusive) of the `type` region > > + */ > > void vm_init_type(enum vmap_region type, void *start, void *end); > > > > +/** > > + * Maps a range of physical ranges onto a single virtual range > > Largely related to it not really being clear what "a range of physical ranges" > actually is, maybe "a set of physical ranges"? Ack. I like your phrasing better. > > > + * `mfn` is an array of `nr` physical ranges, each of which is `granularity` > > + * pages wide. `type` defines which vmap region to use for the mapping and > > + * `flags` is the PTE flags the page table leaves are meant to have. > > + * > > + * Typically used via the vmap() and vmap_contig() helpers. > > + * > > + * @param mfn Array of mfns > > + * @param granularity Number of contiguous pages each mfn represents > > + * @param nr Number of mfns in the `mfn` array > > + * @param align Alignment of the virtual area to map > > + * @param flags PTE flags for the leaves of the PT tree. > > + * @param type Which region to create the mappings on > > + */ > > void *__vmap(const mfn_t *mfn, unsigned int granularity, unsigned int nr, > > unsigned int align, unsigned int flags, enum vmap_region type); > > + > > +/** > > + * Map an arrray of pages contiguously into the VMAP_DEFAULT vmap region > > Nit: One r too many in "array". Sure. > > > + * @param[in] mfn Pointer to the base of an array of mfns > > + * @param[in] nr Number of mfns in the array > > + */ > > void *vmap(const mfn_t *mfn, unsigned int nr); > > + > > +/** > > + * Maps physically contiguous pages onto the VMAP_DEFAULT vmap region > > + * > > + * Used when the directmap is unavailable (i.e: due to secret hiding) > > Please omit this. There's no reason to suggest it can't also be used for > other purposes. Sure. > > > + * @param mfn Base mfn of the physical region > > + * @param nr Number of mfns in the physical region > > + */ > > void *vmap_contig(mfn_t mfn, unsigned int nr); > > + > > +/** > > + * Unmaps a range of virtually contiguous memory from one of the vmap regions > > + * > > + * The system remembers internally how wide the mapping is and unmaps it all. > > + * It also can determine the vmap region type from the `va`. > > + * > > + * @param va Virtual base address of the range to unmap > > + */ > > void vunmap(const void *va); > > > > +/** > > + * Allocate `size` octets of possibly non-contiguous physical memory and map > > + * them contiguously in the VMAP_DEFAULT vmap region > > + * > > + * The system remembers internally how wide the mapping is and unmaps it all. > > This is a verbatim copy of what you say for vunmap(), yet it looks unrelated > here. Maybe you meant to edit it after copy-and-paste? Or maybe this was > meant to go ... Yeah, that shouldn't be there and was meant to go... > > > + * @param size Pointer to the base of an array of mfns > > + * @return Pointer to the mapped area on success; NULL otherwise. > > + */ > > void *vmalloc(size_t size); > > + > > +/** Same as vmalloc(), but for the VMAP_XEN vmap region. */ > > void *vmalloc_xen(size_t size); > > > > +/** Same as vmalloc(), but set the contents to zero before returning */ > > void *vzalloc(size_t size); > > + > > +/** > > + * Unmap and free memory from vmalloc(), vmalloc_xen() or vzalloc() > > + * > > + * @param va Virtual base address of the range to free and unmap > > + */ > > void vfree(void *va); > > ... here? ... there. > > Also, if you want this to be considered for 4.19, please don't forget to Cc > Oleksii. > > Jan Will do on v2. Cheers, Alejandro
diff --git a/xen/include/xen/vmap.h b/xen/include/xen/vmap.h index 0c16baa85f31..2ab8030d6d00 100644 --- a/xen/include/xen/vmap.h +++ b/xen/include/xen/vmap.h @@ -1,34 +1,131 @@ +/* + * Interface to map physical memory onto contiguous virtual memory areas. + * + * Two ranges of linear address space are reserved for this purpose: A general + * purpose area (VMAP_DEFAULT) and a livepatch-specific area (VMAP_XEN). The + * latter is used when loading livepatches and the former for everything else. + */ #if !defined(__XEN_VMAP_H__) && defined(VMAP_VIRT_START) #define __XEN_VMAP_H__ #include <xen/mm-frame.h> #include <xen/page-size.h> +/** Identifiers for the linear ranges tracked by vmap */ enum vmap_region { + /* + * Region used for general purpose RW mappings. Mapping/allocating memory + * here can induce extra allocations for the supporting page tables. + */ VMAP_DEFAULT, + /** + * Region used for loading livepatches. Can't use VMAP_DEFAULT because it + * must live close to the running Xen image. The caller also ensures all + * page tables are already in place with adequate PTE flags. + */ VMAP_XEN, + /** Sentinel value for bounds checking */ VMAP_REGION_NR, }; +/** + * Runtime initialiser for each vmap region type + * + * Must only be called once per vmap region type. + * + * @param type Designation of the region to initialise. + * @param start Start address of the `type` region. + * @param end End address (not inclusive) of the `type` region + */ void vm_init_type(enum vmap_region type, void *start, void *end); +/** + * Maps a range of physical ranges onto a single virtual range + * + * `mfn` is an array of `nr` physical ranges, each of which is `granularity` + * pages wide. `type` defines which vmap region to use for the mapping and + * `flags` is the PTE flags the page table leaves are meant to have. + * + * Typically used via the vmap() and vmap_contig() helpers. + * + * @param mfn Array of mfns + * @param granularity Number of contiguous pages each mfn represents + * @param nr Number of mfns in the `mfn` array + * @param align Alignment of the virtual area to map + * @param flags PTE flags for the leaves of the PT tree. + * @param type Which region to create the mappings on + */ void *__vmap(const mfn_t *mfn, unsigned int granularity, unsigned int nr, unsigned int align, unsigned int flags, enum vmap_region type); + +/** + * Map an arrray of pages contiguously into the VMAP_DEFAULT vmap region + * + * @param[in] mfn Pointer to the base of an array of mfns + * @param[in] nr Number of mfns in the array + */ void *vmap(const mfn_t *mfn, unsigned int nr); + +/** + * Maps physically contiguous pages onto the VMAP_DEFAULT vmap region + * + * Used when the directmap is unavailable (i.e: due to secret hiding) + * + * @param mfn Base mfn of the physical region + * @param nr Number of mfns in the physical region + */ void *vmap_contig(mfn_t mfn, unsigned int nr); + +/** + * Unmaps a range of virtually contiguous memory from one of the vmap regions + * + * The system remembers internally how wide the mapping is and unmaps it all. + * It also can determine the vmap region type from the `va`. + * + * @param va Virtual base address of the range to unmap + */ void vunmap(const void *va); +/** + * Allocate `size` octets of possibly non-contiguous physical memory and map + * them contiguously in the VMAP_DEFAULT vmap region + * + * The system remembers internally how wide the mapping is and unmaps it all. + * + * @param size Pointer to the base of an array of mfns + * @return Pointer to the mapped area on success; NULL otherwise. + */ void *vmalloc(size_t size); + +/** Same as vmalloc(), but for the VMAP_XEN vmap region. */ void *vmalloc_xen(size_t size); +/** Same as vmalloc(), but set the contents to zero before returning */ void *vzalloc(size_t size); + +/** + * Unmap and free memory from vmalloc(), vmalloc_xen() or vzalloc() + * + * @param va Virtual base address of the range to free and unmap + */ void vfree(void *va); +/** + * Analogous to vmap_contig(), but for IO memory + * + * Unlike vmap_contig(), it ensures architecturally correct cacheability + * settings are set for the mapped IO memory. + * + * @param pa Physical base address of the MMIO region. + * @param len Length of the MMIO region in octets. + * @return Pointer to the mapped area on success; NULL otherwise. + */ void __iomem *ioremap(paddr_t pa, size_t len); /* Return the number of pages in the mapping starting at address 'va' */ unsigned int vmap_size(const void *va); +/** Analogous to vunmap(), but for IO memory mapped via ioremap() */ static inline void iounmap(void __iomem *va) { unsigned long addr = (unsigned long)(void __force *)va; @@ -36,7 +133,10 @@ static inline void iounmap(void __iomem *va) vunmap((void *)(addr & PAGE_MASK)); } +/** Pointer to 1 octet past the end of the VMAP_DEFAULT virtual area */ void *arch_vmap_virt_end(void); + +/** Initialises the VMAP_DEFAULT virtual range */ static inline void vm_init(void) { vm_init_type(VMAP_DEFAULT, (void *)VMAP_VIRT_START, arch_vmap_virt_end());
In it's current form it's rather cryptic for uninitiated, so this patch documents everything in there to make it more palatable. No functional change. Signed-off-by: Alejandro Vallejo <alejandro.vallejo@cloud.com> --- xen/include/xen/vmap.h | 100 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 100 insertions(+)