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Re: [Qemu-devel] [PATCH for 2.3 v2 1/1] xen-hvm: increase maxmem before
From: |
Stefano Stabellini |
Subject: |
Re: [Qemu-devel] [PATCH for 2.3 v2 1/1] xen-hvm: increase maxmem before calling xc_domain_populate_physmap |
Date: |
Mon, 12 Jan 2015 11:20:43 +0000 |
User-agent: |
Alpine 2.02 (DEB 1266 2009-07-14) |
On Wed, 3 Dec 2014, Don Slutz wrote:
> From: Stefano Stabellini <address@hidden>
>
> Increase maxmem before calling xc_domain_populate_physmap_exact to
> avoid the risk of running out of guest memory. This way we can also
> avoid complex memory calculations in libxl at domain construction
> time.
>
> This patch fixes an abort() when assigning more than 4 NICs to a VM.
>
> Signed-off-by: Stefano Stabellini <address@hidden>
> Signed-off-by: Don Slutz <address@hidden>
> ---
> v2: Changes by Don Slutz
> Switch from xc_domain_getinfo to xc_domain_getinfolist
> Fix error check for xc_domain_getinfolist
> Limit increase of maxmem to only do when needed:
> Add QEMU_SPARE_PAGES (How many pages to leave free)
> Add free_pages calculation
>
> xen-hvm.c | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> diff --git a/xen-hvm.c b/xen-hvm.c
> index 7548794..d30e77e 100644
> --- a/xen-hvm.c
> +++ b/xen-hvm.c
> @@ -90,6 +90,7 @@ static inline ioreq_t *xen_vcpu_ioreq(shared_iopage_t
> *shared_page, int vcpu)
> #endif
>
> #define BUFFER_IO_MAX_DELAY 100
> +#define QEMU_SPARE_PAGES 16
We need a big comment here to explain why we have this parameter and
when we'll be able to get rid of it.
Other than that the patch is fine.
Thanks!
> typedef struct XenPhysmap {
> hwaddr start_addr;
> @@ -244,6 +245,8 @@ void xen_ram_alloc(ram_addr_t ram_addr, ram_addr_t size,
> MemoryRegion *mr)
> unsigned long nr_pfn;
> xen_pfn_t *pfn_list;
> int i;
> + xc_domaininfo_t info;
> + unsigned long free_pages;
>
> if (runstate_check(RUN_STATE_INMIGRATE)) {
> /* RAM already populated in Xen */
> @@ -266,6 +269,22 @@ void xen_ram_alloc(ram_addr_t ram_addr, ram_addr_t size,
> MemoryRegion *mr)
> pfn_list[i] = (ram_addr >> TARGET_PAGE_BITS) + i;
> }
>
> + if ((xc_domain_getinfolist(xen_xc, xen_domid, 1, &info) != 1) ||
> + (info.domain != xen_domid)) {
> + hw_error("xc_domain_getinfolist failed");
> + }
> + free_pages = info.max_pages - info.tot_pages;
> + if (free_pages > QEMU_SPARE_PAGES) {
> + free_pages -= QEMU_SPARE_PAGES;
> + } else {
> + free_pages = 0;
> + }
> + if ((free_pages < nr_pfn) &&
> + (xc_domain_setmaxmem(xen_xc, xen_domid,
> + ((info.max_pages + nr_pfn - free_pages)
> + << (XC_PAGE_SHIFT - 10))) < 0)) {
> + hw_error("xc_domain_setmaxmem failed");
> + }
> if (xc_domain_populate_physmap_exact(xen_xc, xen_domid, nr_pfn, 0, 0,
> pfn_list)) {
> hw_error("xen: failed to populate ram at " RAM_ADDR_FMT, ram_addr);
> }
> --
> 1.8.4
>