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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: Pavel Tatashin <pasha.tatashin@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Paolo 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
This commit is contained in:
Pavel Tatashin 2018-07-19 16:55:20 -04:00 committed by Thomas Gleixner
parent 73ab603f44
commit 368a540e02
3 changed files with 12 additions and 59 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
arch/x86/kernel/kvm.c
View File

@ -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,
};

66
arch/x86/kernel/kvmclock.c
View File

@ -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;

4
arch/x86/kernel/setup.c
View File

@ -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();