Commit 50d0a0f9 authored by Gerd Hoffmann's avatar Gerd Hoffmann Committed by Avi Kivity
Browse files

KVM: Make kvm host use the paravirt clocksource structs 



This patch updates the kvm host code to use the pvclock structs.
It also makes the paravirt clock compatible with Xen.

Signed-off-by: default avatarGerd Hoffmann <kraxel@redhat.com>
Signed-off-by: default avatarAvi Kivity <avi@qumranet.com>
parent 1c7b67f7

arch/x86/kvm/x86.c

+62 −13
Original line number Diff line number Diff line
@@ -492,8 +492,8 @@ static int do_set_msr(struct kvm_vcpu *vcpu, unsigned index, u64 *data) 
static void kvm_write_wall_clock(struct kvm *kvm, gpa_t wall_clock)

{

	static int version;

	struct kvm_wall_clock wc;

	struct timespec wc_ts;

	struct pvclock_wall_clock wc;

	struct timespec now, sys, boot;



	if (!wall_clock)

		return;
@@ -502,10 +502,19 @@ static void kvm_write_wall_clock(struct kvm *kvm, gpa_t wall_clock) 


	kvm_write_guest(kvm, wall_clock, &version, sizeof(version));



	wc_ts = current_kernel_time();

	wc.wc_sec = wc_ts.tv_sec;

	wc.wc_nsec = wc_ts.tv_nsec;

	wc.wc_version = version;

	/*

	 * The guest calculates current wall clock time by adding

	 * system time (updated by kvm_write_guest_time below) to the

	 * wall clock specified here.  guest system time equals host

	 * system time for us, thus we must fill in host boot time here.

	 */

	now = current_kernel_time();

	ktime_get_ts(&sys);

	boot = ns_to_timespec(timespec_to_ns(&now) - timespec_to_ns(&sys));



	wc.sec = boot.tv_sec;

	wc.nsec = boot.tv_nsec;

	wc.version = version;



	kvm_write_guest(kvm, wall_clock, &wc, sizeof(wc));
@@ -513,6 +522,45 @@ static void kvm_write_wall_clock(struct kvm *kvm, gpa_t wall_clock) 
	kvm_write_guest(kvm, wall_clock, &version, sizeof(version));

}



static uint32_t div_frac(uint32_t dividend, uint32_t divisor)

{

	uint32_t quotient, remainder;



	/* Don't try to replace with do_div(), this one calculates

	 * "(dividend << 32) / divisor" */

	__asm__ ( "divl %4"

		  : "=a" (quotient), "=d" (remainder)

		  : "0" (0), "1" (dividend), "r" (divisor) );

	return quotient;

}



static void kvm_set_time_scale(uint32_t tsc_khz, struct pvclock_vcpu_time_info *hv_clock)

{

	uint64_t nsecs = 1000000000LL;

	int32_t  shift = 0;

	uint64_t tps64;

	uint32_t tps32;



	tps64 = tsc_khz * 1000LL;

	while (tps64 > nsecs*2) {

		tps64 >>= 1;

		shift--;

	}



	tps32 = (uint32_t)tps64;

	while (tps32 <= (uint32_t)nsecs) {

		tps32 <<= 1;

		shift++;

	}



	hv_clock->tsc_shift = shift;

	hv_clock->tsc_to_system_mul = div_frac(nsecs, tps32);



	pr_debug("%s: tsc_khz %u, tsc_shift %d, tsc_mul %u\n",

		 __FUNCTION__, tsc_khz, hv_clock->tsc_shift,

		 hv_clock->tsc_to_system_mul);

}



static void kvm_write_guest_time(struct kvm_vcpu *v)

{

	struct timespec ts;
@@ -523,6 +571,11 @@ static void kvm_write_guest_time(struct kvm_vcpu *v) 
	if ((!vcpu->time_page))

		return;



	if (unlikely(vcpu->hv_clock_tsc_khz != tsc_khz)) {

		kvm_set_time_scale(tsc_khz, &vcpu->hv_clock);

		vcpu->hv_clock_tsc_khz = tsc_khz;

	}



	/* Keep irq disabled to prevent changes to the clock */

	local_irq_save(flags);

	kvm_get_msr(v, MSR_IA32_TIME_STAMP_COUNTER,
@@ -537,9 +590,9 @@ static void kvm_write_guest_time(struct kvm_vcpu *v) 
	/*

	 * The interface expects us to write an even number signaling that the

	 * update is finished. Since the guest won't see the intermediate

	 * state, we just write "2" at the end

	 * state, we just increase by 2 at the end.

	 */

	vcpu->hv_clock.version = 2;

	vcpu->hv_clock.version += 2;



	shared_kaddr = kmap_atomic(vcpu->time_page, KM_USER0);
@@ -599,10 +652,6 @@ int kvm_set_msr_common(struct kvm_vcpu *vcpu, u32 msr, u64 data) 
		/* ...but clean it before doing the actual write */

		vcpu->arch.time_offset = data & ~(PAGE_MASK | 1);



		vcpu->arch.hv_clock.tsc_to_system_mul =

					clocksource_khz2mult(tsc_khz, 22);

		vcpu->arch.hv_clock.tsc_shift = 22;



		down_read(&current->mm->mmap_sem);

		vcpu->arch.time_page =

				gfn_to_page(vcpu->kvm, data >> PAGE_SHIFT);

include/asm-x86/kvm_host.h

+3 −1
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ 
#include <linux/kvm_para.h>

#include <linux/kvm_types.h>



#include <asm/pvclock-abi.h>

#include <asm/desc.h>



#define KVM_MAX_VCPUS 16
@@ -282,7 +283,8 @@ struct kvm_vcpu_arch { 
	struct x86_emulate_ctxt emulate_ctxt;



	gpa_t time;

	struct kvm_vcpu_time_info hv_clock;

	struct pvclock_vcpu_time_info hv_clock;

	unsigned int hv_clock_tsc_khz;

	unsigned int time_offset;

	struct page *time_page;

};