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Commit d7646eaa authored by Vitaly Kuznetsov's avatar Vitaly Kuznetsov Committed by Greg Kroah-Hartman
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Drivers: hv: don't do hypercalls when hypercall_page is NULL 



At the very late stage of kexec a driver (which are not being unloaded) can
try to post a message or signal an event. This will crash the kernel as we
already did hv_cleanup() and the hypercall page is NULL.

Move all common (between 32 and 64 bit code) declarations to the beginning
of the do_hypercall() function. Unfortunately we have to write the
!hypercall_page check twice to not mix declarations and code.

Signed-off-by: default avatarVitaly Kuznetsov <vkuznets@redhat.com>
Signed-off-by: default avatarK. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 2517281d

drivers/hv/hv.c

+8 −5
Original line number Diff line number Diff line
@@ -93,11 +93,14 @@ static int query_hypervisor_info(void) 
 */

static u64 do_hypercall(u64 control, void *input, void *output)

{

#ifdef CONFIG_X86_64

	u64 hv_status = 0;

	u64 input_address = (input) ? virt_to_phys(input) : 0;

	u64 output_address = (output) ? virt_to_phys(output) : 0;

	void *hypercall_page = hv_context.hypercall_page;

#ifdef CONFIG_X86_64

	u64 hv_status = 0;



	if (!hypercall_page)

		return (u64)ULLONG_MAX;



	__asm__ __volatile__("mov %0, %%r8" : : "r" (output_address) : "r8");

	__asm__ __volatile__("call *%3" : "=a" (hv_status) :
@@ -112,13 +115,13 @@ static u64 do_hypercall(u64 control, void *input, void *output) 
	u32 control_lo = control & 0xFFFFFFFF;

	u32 hv_status_hi = 1;

	u32 hv_status_lo = 1;

	u64 input_address = (input) ? virt_to_phys(input) : 0;

	u32 input_address_hi = input_address >> 32;

	u32 input_address_lo = input_address & 0xFFFFFFFF;

	u64 output_address = (output) ? virt_to_phys(output) : 0;

	u32 output_address_hi = output_address >> 32;

	u32 output_address_lo = output_address & 0xFFFFFFFF;

	void *hypercall_page = hv_context.hypercall_page;



	if (!hypercall_page)

		return (u64)ULLONG_MAX;



	__asm__ __volatile__ ("call *%8" : "=d"(hv_status_hi),

			      "=a"(hv_status_lo) : "d" (control_hi),