Commit 05bd330a authored by Dexuan Cui's avatar Dexuan Cui Committed by Thomas Gleixner
Browse files

x86/hyperv: Suspend/resume the hypercall page for hibernation 



For hibernation the hypercall page must be disabled before the hibernation
image is created so that subsequent hypercall operations fail safely. On
resume the hypercall page has to be restored and reenabled to ensure proper
operation of the resumed kernel.

Implement the necessary suspend/resume callbacks.

[ tglx: Decrypted changelog ]

Signed-off-by: default avatarDexuan Cui <decui@microsoft.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reviewed-by: default avatarMichael Kelley <mikelley@microsoft.com>
Link: https://lore.kernel.org/r/1578350559-130275-1-git-send-email-decui@microsoft.com
parent 6f1a4891

arch/x86/hyperv/hv_init.c

+50 −0
Original line number Diff line number Diff line
@@ -21,11 +21,15 @@ 
#include <linux/hyperv.h>

#include <linux/slab.h>

#include <linux/cpuhotplug.h>

#include <linux/syscore_ops.h>

#include <clocksource/hyperv_timer.h>



void *hv_hypercall_pg;

EXPORT_SYMBOL_GPL(hv_hypercall_pg);



/* Storage to save the hypercall page temporarily for hibernation */

static void *hv_hypercall_pg_saved;



u32 *hv_vp_index;

EXPORT_SYMBOL_GPL(hv_vp_index);
@@ -246,6 +250,48 @@ static int __init hv_pci_init(void) 
	return 1;

}



static int hv_suspend(void)

{

	union hv_x64_msr_hypercall_contents hypercall_msr;



	/*

	 * Reset the hypercall page as it is going to be invalidated

	 * accross hibernation. Setting hv_hypercall_pg to NULL ensures

	 * that any subsequent hypercall operation fails safely instead of

	 * crashing due to an access of an invalid page. The hypercall page

	 * pointer is restored on resume.

	 */

	hv_hypercall_pg_saved = hv_hypercall_pg;

	hv_hypercall_pg = NULL;



	/* Disable the hypercall page in the hypervisor */

	rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);

	hypercall_msr.enable = 0;

	wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);



	return 0;

}



static void hv_resume(void)

{

	union hv_x64_msr_hypercall_contents hypercall_msr;



	/* Re-enable the hypercall page */

	rdmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);

	hypercall_msr.enable = 1;

	hypercall_msr.guest_physical_address =

		vmalloc_to_pfn(hv_hypercall_pg_saved);

	wrmsrl(HV_X64_MSR_HYPERCALL, hypercall_msr.as_uint64);



	hv_hypercall_pg = hv_hypercall_pg_saved;

	hv_hypercall_pg_saved = NULL;

}



static struct syscore_ops hv_syscore_ops = {

	.suspend	= hv_suspend,

	.resume		= hv_resume,

};



/*

 * This function is to be invoked early in the boot sequence after the

 * hypervisor has been detected.
@@ -330,6 +376,8 @@ void __init hyperv_init(void) 


	x86_init.pci.arch_init = hv_pci_init;



	register_syscore_ops(&hv_syscore_ops);



	return;



remove_cpuhp_state:
@@ -349,6 +397,8 @@ void hyperv_cleanup(void) 
{

	union hv_x64_msr_hypercall_contents hypercall_msr;



	unregister_syscore_ops(&hv_syscore_ops);



	/* Reset our OS id */

	wrmsrl(HV_X64_MSR_GUEST_OS_ID, 0);

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