[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen master] x86/shadow: Drop dubious lastpage diagnostic
commit b5d8b03db136dca2c7e755cd227265b5be451c88 Author: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> AuthorDate: Fri Jan 20 11:01:52 2023 +0000 Commit: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> CommitDate: Fri Jan 20 19:39:32 2023 +0000 x86/shadow: Drop dubious lastpage diagnostic This is a global variable (actually 3, one per GUEST_PAGING_LEVEL), operated on using atomics only (with no regard to what else shares the same cacheline), which emits a diagnostic (in debug builds only) without changing any program behaviour. It is presumably left-over debugging, as it interlinks the behaviour of all vCPUs in chronological order. Based on the read-only p2m types, this diagnostic can be tripped by entirely legitimate guest behaviour. Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> Acked-by: Jan Beulich <jbeulich@xxxxxxxx> --- xen/arch/x86/mm/shadow/multi.c | 7 ------- 1 file changed, 7 deletions(-) diff --git a/xen/arch/x86/mm/shadow/multi.c b/xen/arch/x86/mm/shadow/multi.c index 8b3e678fa0..3b06cfaf9a 100644 --- a/xen/arch/x86/mm/shadow/multi.c +++ b/xen/arch/x86/mm/shadow/multi.c @@ -2597,14 +2597,7 @@ static int cf_check sh_page_fault( /* Ignore attempts to write to read-only memory. */ if ( p2m_is_readonly(p2mt) && (ft == ft_demand_write) ) - { - static unsigned long lastpage; - if ( xchg(&lastpage, va & PAGE_MASK) != (va & PAGE_MASK) ) - gdprintk(XENLOG_DEBUG, "guest attempted write to read-only memory" - " page. va page=%#lx, mfn=%#lx\n", - va & PAGE_MASK, mfn_x(gmfn)); goto emulate_readonly; /* skip over the instruction */ - } /* In HVM guests, we force CR0.WP always to be set, so that the * pagetables are always write-protected. If the guest thinks -- generated by git-patchbot for /home/xen/git/xen.git#master
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