Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-11-27 06:31:52 +00:00
Code Issues Packages Projects Releases Wiki Activity

KVM/arm64 fixes for 6.3, part #1

Browse Source 
A single patch to address a rather annoying bug w.r.t. guest timer
 offsetting. Effectively the synchronization of timer offsets between
 vCPUs was broken, leading to inconsistent timer reads within the VM.
 -----BEGIN PGP SIGNATURE-----
 
 iHUEABYIAB0WIQSNXHjWXuzMZutrKNKivnWIJHzdFgUCZAzwRwAKCRCivnWIJHzd
 Fh0nAP4seI9aMrv0EnCHS9nufCSYQZYGBxOe+8EyUOIERxyCPgEAspn6fNJWnc6o
 RWbFGMyNHPgeQgGjH+g4ehqh5LSeMww=
 =uFU2
 -----END PGP SIGNATURE-----

Merge tag 'kvmarm-fixes-6.3-1' of git://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm into HEAD

KVM/arm64 fixes for 6.3, part #1

A single patch to address a rather annoying bug w.r.t. guest timer
offsetting. Effectively the synchronization of timer offsets between
vCPUs was broken, leading to inconsistent timer reads within the VM.
This commit is contained in:
Paolo Bonzini 2023-03-14 09:40:39 -04:00
commit bceeedb2f0
4 changed files with 29 additions and 36 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

3
arch/arm64/include/asm/kvm_host.h
View File

@ -193,6 +193,9 @@ struct kvm_arch {
/* Interrupt controller */
struct vgic_dist vgic;
/* Timers */
struct arch_timer_vm_data timer_data;
/* Mandated version of PSCI */
u32 psci_version;

45
arch/arm64/kvm/arch_timer.c
View File

@ -84,14 +84,10 @@ u64 timer_get_cval(struct arch_timer_context *ctxt)
static u64 timer_get_offset(struct arch_timer_context *ctxt)
{
struct kvm_vcpu *vcpu = ctxt->vcpu;
if (ctxt->offset.vm_offset)
return *ctxt->offset.vm_offset;
switch(arch_timer_ctx_index(ctxt)) {
case TIMER_VTIMER:
return __vcpu_sys_reg(vcpu, CNTVOFF_EL2);
default:
return 0;
}
return 0;
}
static void timer_set_ctl(struct arch_timer_context *ctxt, u32 ctl)
@ -128,15 +124,12 @@ static void timer_set_cval(struct arch_timer_context *ctxt, u64 cval)
static void timer_set_offset(struct arch_timer_context *ctxt, u64 offset)
{
struct kvm_vcpu *vcpu = ctxt->vcpu;
switch(arch_timer_ctx_index(ctxt)) {
case TIMER_VTIMER:
__vcpu_sys_reg(vcpu, CNTVOFF_EL2) = offset;
break;
default:
if (!ctxt->offset.vm_offset) {
WARN(offset, "timer %ld\n", arch_timer_ctx_index(ctxt));
return;
}
WRITE_ONCE(*ctxt->offset.vm_offset, offset);
}
u64 kvm_phys_timer_read(void)
@ -765,25 +758,6 @@ int kvm_timer_vcpu_reset(struct kvm_vcpu *vcpu)
return 0;
}
/* Make the updates of cntvoff for all vtimer contexts atomic */
static void update_vtimer_cntvoff(struct kvm_vcpu *vcpu, u64 cntvoff)
{
unsigned long i;
struct kvm *kvm = vcpu->kvm;
struct kvm_vcpu *tmp;
mutex_lock(&kvm->lock);
kvm_for_each_vcpu(i, tmp, kvm)
timer_set_offset(vcpu_vtimer(tmp), cntvoff);
/*
* When called from the vcpu create path, the CPU being created is not
* included in the loop above, so we just set it here as well.
*/
timer_set_offset(vcpu_vtimer(vcpu), cntvoff);
mutex_unlock(&kvm->lock);
}
void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
{
struct arch_timer_cpu *timer = vcpu_timer(vcpu);
@ -791,10 +765,11 @@ void kvm_timer_vcpu_init(struct kvm_vcpu *vcpu)
struct arch_timer_context *ptimer = vcpu_ptimer(vcpu);
vtimer->vcpu = vcpu;
vtimer->offset.vm_offset = &vcpu->kvm->arch.timer_data.voffset;
ptimer->vcpu = vcpu;
/* Synchronize cntvoff across all vtimers of a VM. */
update_vtimer_cntvoff(vcpu, kvm_phys_timer_read());
timer_set_offset(vtimer, kvm_phys_timer_read());
timer_set_offset(ptimer, 0);
hrtimer_init(&timer->bg_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_HARD);
@ -840,7 +815,7 @@ int kvm_arm_timer_set_reg(struct kvm_vcpu *vcpu, u64 regid, u64 value)
break;
case KVM_REG_ARM_TIMER_CNT:
timer = vcpu_vtimer(vcpu);
update_vtimer_cntvoff(vcpu, kvm_phys_timer_read() - value);
timer_set_offset(timer, kvm_phys_timer_read() - value);
break;
case KVM_REG_ARM_TIMER_CVAL:
timer = vcpu_vtimer(vcpu);

2
arch/arm64/kvm/hypercalls.c
View File

@ -44,7 +44,7 @@ static void kvm_ptp_get_time(struct kvm_vcpu *vcpu, u64 *val)
feature = smccc_get_arg1(vcpu);
switch (feature) {
case KVM_PTP_VIRT_COUNTER:
cycles = systime_snapshot.cycles - vcpu_read_sys_reg(vcpu, CNTVOFF_EL2);
cycles = systime_snapshot.cycles - vcpu->kvm->arch.timer_data.voffset;
break;
case KVM_PTP_PHYS_COUNTER:
cycles = systime_snapshot.cycles;

15
include/kvm/arm_arch_timer.h
View File

@ -23,6 +23,19 @@ enum kvm_arch_timer_regs {
TIMER_REG_CTL,
};
struct arch_timer_offset {
/*
* If set, pointer to one of the offsets in the kvm's offset
* structure. If NULL, assume a zero offset.
*/
u64 *vm_offset;
};
struct arch_timer_vm_data {
/* Offset applied to the virtual timer/counter */
u64 voffset;
};
struct arch_timer_context {
struct kvm_vcpu *vcpu;
@ -32,6 +45,8 @@ struct arch_timer_context {
/* Emulated Timer (may be unused) */
struct hrtimer hrtimer;
/* Offset for this counter/timer */
struct arch_timer_offset offset;
/*
* We have multiple paths which can save/restore the timer state onto
* the hardware, so we need some way of keeping track of where the