[PATCH v13 05/18] kvm/x86: remove kvm memblock dependency

[Pavel Tatashin <pasha.tatashin@oracle.com>]

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

Lets bring it inline with other hypervisors by removing this dependency by
using memory from BSS instead of allocating it.

The benefits:
- remove ifdef from common code
- earlier availability of TSC.
- remove dependency on memblock, and reduce code
- earlier kvm sched_clock()

Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
---
 arch/x86/include/asm/kvm_para.h |  2 +-
 arch/x86/kernel/kvm.c           |  1 +
 arch/x86/kernel/kvmclock.c      | 66 +++++----------------------------
 arch/x86/kernel/setup.c         |  7 +---
 4 files changed, 14 insertions(+), 62 deletions(-)

diff --git a/arch/x86/include/asm/kvm_para.h b/arch/x86/include/asm/kvm_para.h
index 3aea2658323a..62872a862914 100644
--- a/arch/x86/include/asm/kvm_para.h
+++ b/arch/x86/include/asm/kvm_para.h
@@ -6,7 +6,7 @@
 #include <asm/alternative.h>
 #include <uapi/asm/kvm_para.h>
 
-extern void kvmclock_init(void);
+extern void kvm_platform_init(void);
 extern int kvm_register_clock(char *txt);
 
 #ifdef CONFIG_KVM_GUEST
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 5b2300b818af..874c53dd8ba2 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -628,6 +628,7 @@ const __initconst struct hypervisor_x86 x86_hyper_kvm = {
 	.name			= "KVM",
 	.detect			= kvm_detect,
 	.type			= X86_HYPER_KVM,
+	.init.init_platform	= kvm_platform_init,
 	.init.guest_late_init	= kvm_guest_init,
 	.init.x2apic_available	= kvm_para_available,
 };
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index bf8d1eb7fca3..d2af1b1f060e 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -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 +44,11 @@ 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;
@@ -244,43 +249,12 @@ 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)
+void __init kvm_platform_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;
 
@@ -290,28 +264,11 @@ 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;
 	}
@@ -354,13 +311,10 @@ 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;
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 403b2d2c31d2..01fcc8bf7c8f 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1014,6 +1014,8 @@ void __init setup_arch(char **cmdline_p)
 	 */
 	init_hypervisor_platform();
 
+	tsc_early_delay_calibrate();
+
 	x86_init.resources.probe_roms();
 
 	/* after parse_early_param, so could debug it */
@@ -1199,11 +1201,6 @@ 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();
 
-- 
2.18.0