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KVM: PPC: Book3S HV: Add a function to filter guest LPCR bits

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Guest LPCR depends on hardware type, and future changes will add
restrictions based on errata and guest MMU mode. Move this logic
to a common function and use it for the cases where the guest
wants to update its LPCR (or the LPCR of a nested guest).

This also adds a warning in other places that set or update LPCR
if we try to set something that would have been disallowed by
the filter, as a sanity check.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Fabiano Rosas <farosas@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210412014845.1517916-4-npiggin@gmail.com
This commit is contained in:
Nicholas Piggin 2021-04-12 11:48:36 +10:00 committed by Michael Ellerman
parent a19b70abc6
commit 67145ef496
3 changed files with 59 additions and 19 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

2
arch/powerpc/include/asm/kvm_book3s.h
View file

@ -258,6 +258,8 @@ extern long kvmppc_hv_get_dirty_log_hpt(struct kvm *kvm,
extern void kvmppc_harvest_vpa_dirty(struct kvmppc_vpa *vpa,
struct kvm_memory_slot *memslot,
unsigned long *map);
extern unsigned long kvmppc_filter_lpcr_hv(struct kvm *kvm,
unsigned long lpcr);
extern void kvmppc_update_lpcr(struct kvm *kvm, unsigned long lpcr,
unsigned long mask);
extern void kvmppc_set_fscr(struct kvm_vcpu *vcpu, u64 fscr);

68
arch/powerpc/kvm/book3s_hv.c
View file

@ -1635,6 +1635,35 @@ static int kvm_arch_vcpu_ioctl_set_sregs_hv(struct kvm_vcpu *vcpu,
return 0;
}
/*
* Enforce limits on guest LPCR values based on hardware availability,
* guest configuration, and possibly hypervisor support and security
* concerns.
*/
unsigned long kvmppc_filter_lpcr_hv(struct kvm *kvm, unsigned long lpcr)
{
/* On POWER8 and above, userspace can modify AIL */
if (!cpu_has_feature(CPU_FTR_ARCH_207S))
lpcr &= ~LPCR_AIL;
/*
* On POWER9, allow userspace to enable large decrementer for the
* guest, whether or not the host has it enabled.
*/
if (!cpu_has_feature(CPU_FTR_ARCH_300))
lpcr &= ~LPCR_LD;
return lpcr;
}
static void verify_lpcr(struct kvm *kvm, unsigned long lpcr)
{
if (lpcr != kvmppc_filter_lpcr_hv(kvm, lpcr)) {
WARN_ONCE(1, "lpcr 0x%lx differs from filtered 0x%lx\n",
lpcr, kvmppc_filter_lpcr_hv(kvm, lpcr));
}
}
static void kvmppc_set_lpcr(struct kvm_vcpu *vcpu, u64 new_lpcr,
bool preserve_top32)
{
@ -1643,6 +1672,23 @@ static void kvmppc_set_lpcr(struct kvm_vcpu *vcpu, u64 new_lpcr,
u64 mask;
spin_lock(&vc->lock);
/*
* Userspace can only modify
* DPFD (default prefetch depth), ILE (interrupt little-endian),
* TC (translation control), AIL (alternate interrupt location),
* LD (large decrementer).
* These are subject to restrictions from kvmppc_filter_lcpr_hv().
*/
mask = LPCR_DPFD | LPCR_ILE | LPCR_TC | LPCR_AIL | LPCR_LD;
/* Broken 32-bit version of LPCR must not clear top bits */
if (preserve_top32)
mask &= 0xFFFFFFFF;
new_lpcr = kvmppc_filter_lpcr_hv(kvm,
(vc->lpcr & ~mask) | (new_lpcr & mask));
/*
* If ILE (interrupt little-endian) has changed, update the
* MSR_LE bit in the intr_msr for each vcpu in this vcore.
@ -1661,25 +1707,8 @@ static void kvmppc_set_lpcr(struct kvm_vcpu *vcpu, u64 new_lpcr,
}
}
/*
* Userspace can only modify DPFD (default prefetch depth),
* ILE (interrupt little-endian) and TC (translation control).
* On POWER8 and POWER9 userspace can also modify AIL (alt. interrupt loc.).
*/
mask = LPCR_DPFD | LPCR_ILE | LPCR_TC;
if (cpu_has_feature(CPU_FTR_ARCH_207S))
mask |= LPCR_AIL;
/*
* On POWER9, allow userspace to enable large decrementer for the
* guest, whether or not the host has it enabled.
*/
if (cpu_has_feature(CPU_FTR_ARCH_300))
mask |= LPCR_LD;
vc->lpcr = new_lpcr;
/* Broken 32-bit version of LPCR must not clear top bits */
if (preserve_top32)
mask &= 0xFFFFFFFF;
vc->lpcr = (vc->lpcr & ~mask) | (new_lpcr & mask);
spin_unlock(&vc->lock);
}
@ -4644,8 +4673,10 @@ void kvmppc_update_lpcr(struct kvm *kvm, unsigned long lpcr, unsigned long mask)
struct kvmppc_vcore *vc = kvm->arch.vcores[i];
if (!vc)
continue;
spin_lock(&vc->lock);
vc->lpcr = (vc->lpcr & ~mask) | lpcr;
verify_lpcr(kvm, vc->lpcr);
spin_unlock(&vc->lock);
if (++cores_done >= kvm->arch.online_vcores)
break;
@ -4973,6 +5004,7 @@ static int kvmppc_core_init_vm_hv(struct kvm *kvm)
kvmppc_setup_partition_table(kvm);
}
verify_lpcr(kvm, lpcr);
kvm->arch.lpcr = lpcr;
/* Initialization for future HPT resizes */

8
arch/powerpc/kvm/book3s_hv_nested.c
View file

@ -151,7 +151,13 @@ static void sanitise_hv_regs(struct kvm_vcpu *vcpu, struct hv_guest_state *hr)
*/
mask = LPCR_DPFD | LPCR_ILE | LPCR_TC | LPCR_AIL | LPCR_LD |
LPCR_LPES | LPCR_MER;
hr->lpcr = (vc->lpcr & ~mask) | (hr->lpcr & mask);
/*
* Additional filtering is required depending on hardware
* and configuration.
*/
hr->lpcr = kvmppc_filter_lpcr_hv(vcpu->kvm,
(vc->lpcr & ~mask) | (hr->lpcr & mask));
/*
* Don't let L1 enable features for L2 which we've disabled for L1,