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Commit 368a540e authored by Pavel Tatashin's avatar Pavel Tatashin Committed by Thomas Gleixner
Browse files

x86/kvmclock: Remove memblock dependency 



KVM clock is initialized later compared to other hypervisor clocks because
it has a dependency on the memblock allocator.

Bring it in line with other hypervisors by using memory from the BSS
instead of allocating it.

The benefits:

  - Remove ifdef from common code
  - Earlier availability of the clock
  - Remove dependency on memblock, and reduce code

The downside:

  - Static allocation of the per cpu data structures sized NR_CPUS * 64byte
    Will be addressed in follow up patches.

[ tglx: Split out from larger series ]

Signed-off-by: default avatarPavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: default avatarThomas Gleixner <tglx@linutronix.de>
Acked-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
Cc: steven.sistare@oracle.com
Cc: daniel.m.jordan@oracle.com
Cc: linux@armlinux.org.uk
Cc: schwidefsky@de.ibm.com
Cc: heiko.carstens@de.ibm.com
Cc: john.stultz@linaro.org
Cc: sboyd@codeaurora.org
Cc: hpa@zytor.com
Cc: douly.fnst@cn.fujitsu.com
Cc: peterz@infradead.org
Cc: prarit@redhat.com
Cc: feng.tang@intel.com
Cc: pmladek@suse.com
Cc: gnomes@lxorguk.ukuu.org.uk
Cc: linux-s390@vger.kernel.org
Cc: boris.ostrovsky@oracle.com
Cc: jgross@suse.com
Link: https://lkml.kernel.org/r/20180719205545.16512-2-pasha.tatashin@oracle.com
parent 73ab603f

arch/x86/kernel/kvm.c

+1 −0
Original line number Diff line number Diff line
@@ -628,6 +628,7 @@ const __initconst struct hypervisor_x86 x86_hyper_kvm = { 
	.name			= "KVM",

	.detect			= kvm_detect,

	.type			= X86_HYPER_KVM,

	.init.init_platform	= kvmclock_init,

	.init.guest_late_init	= kvm_guest_init,

	.init.x2apic_available	= kvm_para_available,

};

arch/x86/kernel/kvmclock.c

+11 −55
Original line number Diff line number Diff line
@@ -23,9 +23,9 @@ 
#include <asm/apic.h>

#include <linux/percpu.h>

#include <linux/hardirq.h>

#include <linux/memblock.h>

#include <linux/sched.h>

#include <linux/sched/clock.h>

#include <linux/mm.h>



#include <asm/mem_encrypt.h>

#include <asm/x86_init.h>
@@ -44,6 +44,13 @@ static int parse_no_kvmclock(char *arg) 
}

early_param("no-kvmclock", parse_no_kvmclock);



/* Aligned to page sizes to match whats mapped via vsyscalls to userspace */

#define HV_CLOCK_SIZE	(sizeof(struct pvclock_vsyscall_time_info) * NR_CPUS)

#define WALL_CLOCK_SIZE	(sizeof(struct pvclock_wall_clock))



static u8 hv_clock_mem[PAGE_ALIGN(HV_CLOCK_SIZE)] __aligned(PAGE_SIZE);

static u8 wall_clock_mem[PAGE_ALIGN(WALL_CLOCK_SIZE)] __aligned(PAGE_SIZE);



/* The hypervisor will put information about time periodically here */

static struct pvclock_vsyscall_time_info *hv_clock;

static struct pvclock_wall_clock *wall_clock;
@@ -245,43 +252,12 @@ static void kvm_shutdown(void) 
	native_machine_shutdown();

}



static phys_addr_t __init kvm_memblock_alloc(phys_addr_t size,

					     phys_addr_t align)

{

	phys_addr_t mem;



	mem = memblock_alloc(size, align);

	if (!mem)

		return 0;



	if (sev_active()) {

		if (early_set_memory_decrypted((unsigned long)__va(mem), size))

			goto e_free;

	}



	return mem;

e_free:

	memblock_free(mem, size);

	return 0;

}



static void __init kvm_memblock_free(phys_addr_t addr, phys_addr_t size)

{

	if (sev_active())

		early_set_memory_encrypted((unsigned long)__va(addr), size);



	memblock_free(addr, size);

}



void __init kvmclock_init(void)

{

	struct pvclock_vcpu_time_info *vcpu_time;

	unsigned long mem, mem_wall_clock;

	int size, cpu, wall_clock_size;

	int cpu;

	u8 flags;



	size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);



	if (!kvm_para_available())

		return;
@@ -291,28 +267,11 @@ void __init kvmclock_init(void) 
	} else if (!(kvmclock && kvm_para_has_feature(KVM_FEATURE_CLOCKSOURCE)))

		return;



	wall_clock_size = PAGE_ALIGN(sizeof(struct pvclock_wall_clock));

	mem_wall_clock = kvm_memblock_alloc(wall_clock_size, PAGE_SIZE);

	if (!mem_wall_clock)

		return;



	wall_clock = __va(mem_wall_clock);

	memset(wall_clock, 0, wall_clock_size);



	mem = kvm_memblock_alloc(size, PAGE_SIZE);

	if (!mem) {

		kvm_memblock_free(mem_wall_clock, wall_clock_size);

		wall_clock = NULL;

		return;

	}



	hv_clock = __va(mem);

	memset(hv_clock, 0, size);

	wall_clock = (struct pvclock_wall_clock *)wall_clock_mem;

	hv_clock = (struct pvclock_vsyscall_time_info *)hv_clock_mem;



	if (kvm_register_clock("primary cpu clock")) {

		hv_clock = NULL;

		kvm_memblock_free(mem, size);

		kvm_memblock_free(mem_wall_clock, wall_clock_size);

		wall_clock = NULL;

		return;

	}
@@ -357,13 +316,10 @@ int __init kvm_setup_vsyscall_timeinfo(void) 
	int cpu;

	u8 flags;

	struct pvclock_vcpu_time_info *vcpu_time;

	unsigned int size;



	if (!hv_clock)

		return 0;



	size = PAGE_ALIGN(sizeof(struct pvclock_vsyscall_time_info)*NR_CPUS);



	cpu = get_cpu();



	vcpu_time = &hv_clock[cpu].pvti;

arch/x86/kernel/setup.c

+0 −4
Original line number Diff line number Diff line
@@ -1197,10 +1197,6 @@ void __init setup_arch(char **cmdline_p) 


	memblock_find_dma_reserve();



#ifdef CONFIG_KVM_GUEST

	kvmclock_init();

#endif



	tsc_early_delay_calibrate();

	if (!early_xdbc_setup_hardware())

		early_xdbc_register_console();