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Commit a20316d2 authored by Glauber Costa's avatar Glauber Costa Committed by Avi Kivity
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KVM guest: fix bogus wallclock physical address calculation 



The use of __pa() to calculate the address of a C-visible symbol
is wrong, and can lead to unpredictable results. See arch/x86/include/asm/page.h
for details.

It should be replaced with __pa_symbol(), that does the correct math here,
by taking relocations into account.  This ensures the correct wallclock data
structure physical address is passed to the hypervisor.

Cc: stable@kernel.org
Signed-off-by: default avatarGlauber Costa <glommer@redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 5fff7d27

arch/x86/kernel/kvmclock.c

+2 −2
Original line number Original line Diff line number Diff line
@@ -50,8 +50,8 @@ static unsigned long kvm_get_wallclock(void) 
	struct timespec ts;

	struct timespec ts;

	int low, high;

	int low, high;





	low = (int)__pa(&wall_clock);

	low = (int)__pa_symbol(&wall_clock);

	high = ((u64)__pa(&wall_clock) >> 32);

	high = ((u64)__pa_symbol(&wall_clock) >> 32);

	native_write_msr(MSR_KVM_WALL_CLOCK, low, high);

	native_write_msr(MSR_KVM_WALL_CLOCK, low, high);





	vcpu_time = &get_cpu_var(hv_clock);

	vcpu_time = &get_cpu_var(hv_clock);