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SubjectRe: [PATCH V10 05/14] xen/pvh: balloon and grant changes.
On Thu, 12 Dec 2013, Konrad Rzeszutek Wilk wrote:
> From: Mukesh Rathor <mukesh.rathor@oracle.com>
>
> For balloon changes we skip setting of local P2M as it's updated
> in Xen. For grant, the shared grant frame is the PFN and not MFN,
> hence its mapped via the same code path as HVM.
>
> Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
> [v1: Rebase on v3.7-rc3]
> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> CC: <stefano.stabellini@eu.citrix.com>
> Conflicts:
> drivers/xen/balloon.c
> [v2: Rebase on v3.13-rc3 has lot of ARM changes.]
> ---
> drivers/xen/balloon.c | 37 ++++++++++++++++++++-----------------
> drivers/xen/gntdev.c | 3 ++-
> drivers/xen/grant-table.c | 25 ++++++++++++++++++++++---
> 3 files changed, 44 insertions(+), 21 deletions(-)
>
> diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
> index 55ea73f..0e9875a 100644
> --- a/drivers/xen/balloon.c
> +++ b/drivers/xen/balloon.c
> @@ -354,7 +354,9 @@ static enum bp_state increase_reservation(unsigned long nr_pages)
>
> #ifdef CONFIG_XEN_HAVE_PVMMU
> /* Link back into the page tables if not highmem. */
> - if (xen_pv_domain() && !PageHighMem(page)) {
> + if (xen_pv_domain() && !PageHighMem(page) &&
> + !xen_feature(XENFEAT_auto_translated_physmap)) {
> +
> int ret;
> ret = HYPERVISOR_update_va_mapping(
> (unsigned long)__va(pfn << PAGE_SHIFT),
> @@ -411,28 +413,29 @@ static enum bp_state decrease_reservation(unsigned long nr_pages, gfp_t gfp)
>
> scrub_page(page);
>
> - /*
> - * Ballooned out frames are effectively replaced with
> - * a scratch frame. Ensure direct mappings and the
> - * p2m are consistent.
> - */
> - scratch_page = get_balloon_scratch_page();
> + if (!xen_feature(XENFEAT_auto_translated_physmap)) {
> + unsigned long p;
> +
> + /*
> + * Ballooned out frames are effectively replaced with
> + * a scratch frame. Ensure direct mappings and the
> + * p2m are consistent.
> + */
> + scratch_page = get_balloon_scratch_page();
> #ifdef CONFIG_XEN_HAVE_PVMMU
> - if (xen_pv_domain() && !PageHighMem(page)) {
> - ret = HYPERVISOR_update_va_mapping(
> - (unsigned long)__va(pfn << PAGE_SHIFT),
> - pfn_pte(page_to_pfn(scratch_page),
> + if (xen_pv_domain() && !PageHighMem(page)) {
> + ret = HYPERVISOR_update_va_mapping(
> + (unsigned long)__va(pfn << PAGE_SHIFT),
> + pfn_pte(page_to_pfn(scratch_page),
> PAGE_KERNEL_RO), 0);
> - BUG_ON(ret);
> - }
> + BUG_ON(ret);
> + }
> #endif
> - if (!xen_feature(XENFEAT_auto_translated_physmap)) {
> - unsigned long p;
> p = page_to_pfn(scratch_page);
> __set_phys_to_machine(pfn, pfn_to_mfn(p));
> - }
> - put_balloon_scratch_page();
>
> + put_balloon_scratch_page();
> + }
> balloon_append(pfn_to_page(pfn));
> }

These changes to balloon.c are similar to my patch but:

- they don't prevent set_phys_to_machine from being called by
increase_reservation for auto_translated guests

- they don't prevent wasteful balloon_scratch_page from being allocated
for auto_translated guests

I think that it would be best to take my patch instead.



> diff --git a/drivers/xen/gntdev.c b/drivers/xen/gntdev.c
> index e41c79c..c1ae3ce 100644
> --- a/drivers/xen/gntdev.c
> +++ b/drivers/xen/gntdev.c
> @@ -846,7 +846,8 @@ static int __init gntdev_init(void)
> if (!xen_domain())
> return -ENODEV;
>
> - use_ptemod = xen_pv_domain();
> + use_ptemod = xen_pv_domain() &&
> + !xen_feature(XENFEAT_auto_translated_physmap);
>
> err = misc_register(&gntdev_miscdev);
> if (err != 0) {

you might actually just want to have:

use_ptemod = !xen_feature(XENFEAT_auto_translated_physmap);




> diff --git a/drivers/xen/grant-table.c b/drivers/xen/grant-table.c
> index 0283871..1fcf75b 100644
> --- a/drivers/xen/grant-table.c
> +++ b/drivers/xen/grant-table.c
> @@ -1056,14 +1056,20 @@ static void gnttab_unmap_frames_v2(void)
> static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
> {
> struct gnttab_setup_table setup;
> + unsigned long start_gpfn;
> xen_pfn_t *frames;
> unsigned int nr_gframes = end_idx + 1;
> int rc;
>
> - if (xen_hvm_domain()) {
> + if (xen_hvm_domain() || xen_feature(XENFEAT_auto_translated_physmap)) {
> struct xen_add_to_physmap xatp;
> unsigned int i = end_idx;
> rc = 0;
> +
> + if (xen_hvm_domain())
> + start_gpfn = xen_hvm_resume_frames >> PAGE_SHIFT;
> + else
> + start_gpfn = virt_to_pfn(gnttab_shared.addr);
> /*
> * Loop backwards, so that the first hypercall has the largest
> * index, ensuring that the table will grow only once.
> @@ -1072,7 +1078,7 @@ static int gnttab_map(unsigned int start_idx, unsigned int end_idx)
> xatp.domid = DOMID_SELF;
> xatp.idx = i;
> xatp.space = XENMAPSPACE_grant_table;
> - xatp.gpfn = (xen_hvm_resume_frames >> PAGE_SHIFT) + i;
> + xatp.gpfn = start_gpfn + i;
> rc = HYPERVISOR_memory_op(XENMEM_add_to_physmap, &xatp);
> if (rc != 0) {
> pr_warn("grant table add_to_physmap failed, err=%d\n",
> @@ -1135,7 +1141,7 @@ static void gnttab_request_version(void)
> int rc;
> struct gnttab_set_version gsv;
>
> - if (xen_hvm_domain())
> + if (xen_hvm_domain() || xen_feature(XENFEAT_auto_translated_physmap))
> gsv.version = 1;
> else
> gsv.version = 2;
> @@ -1164,11 +1170,24 @@ static void gnttab_request_version(void)
> static int gnttab_setup(void)
> {
> unsigned int max_nr_gframes;
> + char *kmsg = "Failed to kmalloc pages for pv in hvm grant frames\n";
>
> max_nr_gframes = gnttab_max_grant_frames();
> if (max_nr_gframes < nr_grant_frames)
> return -ENOSYS;
>
> + /* PVH note: xen will free existing kmalloc'd mfn in
> + * XENMEM_add_to_physmap. TBD/FIXME: use xen ballooning instead of
> + * kmalloc(). */
> + if (xen_pv_domain() && xen_feature(XENFEAT_auto_translated_physmap) &&
> + !gnttab_shared.addr) {
> + gnttab_shared.addr =
> + kmalloc(max_nr_gframes * PAGE_SIZE, GFP_KERNEL);
> + if (!gnttab_shared.addr) {
> + pr_warn("%s", kmsg);
> + return -ENOMEM;
> + }
> + }
> if (xen_pv_domain())
> return gnttab_map(0, nr_grant_frames - 1);

Can't you just use xen_hvm_resume_frames instead? Just rename it
xen_auto_translated_frames and allocate memory to it from
arch/x86/xen/enlighten.c.
Then you can completely unify the hvm and pvh code paths in this file,
as a result all the

if (xen_hvm_domain() || xen_feature(XENFEAT_auto_translated_physmap))

tests, could be reduced to

if (xen_feature(XENFEAT_auto_translated_physmap))


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