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x86/mem_sharing: don't try to unshare twice during page fault
The page was already tried to be unshared in get_gfn_type_access. If that didn't work, then trying again is pointless. Don't try to send vm_event again either, simply check if there is a ring or not. Signed-off-by: Tamas K Lengyel <tamas.lengyel@intel.com> Acked-by: Jan Beulich <jbeulich@suse.com>
This commit is contained in:
Tamas K Lengyel authored and 
Jan Beulich committed
1 parent
f268900fbc
commit
e6fcf0efe4
1 file changed
+15
-10
+15
-10
@@ -38,6 +38,7 @@
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#include <xen/warning.h>
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#include <xen/vpci.h>
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#include <xen/nospec.h>
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#include <xen/vm_event.h>
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#include <asm/shadow.h>
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#include <asm/hap.h>
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#include <asm/current.h>
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@@ -1702,7 +1703,7 @@ int hvm_hap_nested_page_fault(paddr_t gpa, unsigned long gla,
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struct domain *currd = curr->domain;
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struct p2m_domain *p2m, *hostp2m;
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int rc, fall_through = 0, paged = 0;
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int sharing_enomem = 0;
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bool sharing_enomem = false;
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vm_event_request_t *req_ptr = NULL;
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bool sync = false;
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unsigned int page_order;
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@@ -1894,14 +1895,16 @@ int hvm_hap_nested_page_fault(paddr_t gpa, unsigned long gla,
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if ( p2m_is_paged(p2mt) || (p2mt == p2m_ram_paging_out) )
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paged = 1;
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/* Mem sharing: unshare the page and try again */
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if ( npfec.write_access && (p2mt == p2m_ram_shared) )
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#ifdef CONFIG_MEM_SHARING
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/* Mem sharing: if still shared on write access then its enomem */
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if ( npfec.write_access && p2m_is_shared(p2mt) )
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{
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ASSERT(p2m_is_hostp2m(p2m));
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sharing_enomem = mem_sharing_unshare_page(currd, gfn);
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sharing_enomem = true;
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rc = 1;
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goto out_put_gfn;
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}
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#endif
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/* Spurious fault? PoD and log-dirty also take this path. */
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if ( p2m_is_ram(p2mt) )
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@@ -1955,19 +1958,21 @@ int hvm_hap_nested_page_fault(paddr_t gpa, unsigned long gla,
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*/
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if ( paged )
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p2m_mem_paging_populate(currd, gfn);
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if ( sharing_enomem )
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{
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int rv;
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if ( (rv = mem_sharing_notify_enomem(currd, gfn, true)) < 0 )
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#ifdef CONFIG_MEM_SHARING
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if ( !vm_event_check_ring(currd->vm_event_share) )
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{
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gdprintk(XENLOG_ERR, "Domain %hu attempt to unshare "
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"gfn %lx, ENOMEM and no helper (rc %d)\n",
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currd->domain_id, gfn, rv);
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gprintk(XENLOG_ERR, "Domain %pd attempt to unshare "
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"gfn %lx, ENOMEM and no helper\n",
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currd, gfn);
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/* Crash the domain */
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rc = 0;
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}
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#endif
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}
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if ( req_ptr )
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{
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if ( monitor_traps(curr, sync, req_ptr) < 0 )
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