Re: [PATCH v3 28/33] KVM: PPC: Book3S HV: Sanitise hv_regs on nested guest entry
From: David Gibson <hidden>
Date: 2018-10-03 06:24:45
Also in:
kvm
On Tue, Oct 02, 2018 at 09:31:27PM +1000, Paul Mackerras wrote:
From: Suraj Jitindar Singh <sjitindarsingh@gmail.com> restore_hv_regs() is used to copy the hv_regs L1 wants to set to run the nested (L2) guest into the vcpu structure. We need to sanitise these values to ensure we don't let the L1 guest hypervisor do things we don't want it to. We don't let data address watchpoints or completed instruction address breakpoints be set to match in hypervisor state. We also don't let L1 enable features in the hypervisor facility status and control register (HFSCR) for L2 which we have disabled for L1. That is L2 will get the subset of features which the L0 hypervisor has enabled for L1 and the features L1 wants to enable for L2. This could mean we give L1 a hypervisor facility unavailable interrupt for a facility it thinks it has enabled, however it shouldn't have enabled a facility it itself doesn't have for the L2 guest. We sanitise the registers when copying in the L2 hv_regs. We don't need to sanitise when copying back the L1 hv_regs since these shouldn't be able to contain invalid values as they're just what was copied out. Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com> Signed-off-by: Paul Mackerras <redacted>
Reviewed-by: David Gibson <redacted>
quoted hunk ↗ jump to hunk
--- arch/powerpc/include/asm/reg.h | 1 + arch/powerpc/kvm/book3s_hv_nested.c | 17 +++++++++++++++++ 2 files changed, 18 insertions(+)diff --git a/arch/powerpc/include/asm/reg.h b/arch/powerpc/include/asm/reg.h index 9c42abf..47489f6 100644 --- a/arch/powerpc/include/asm/reg.h +++ b/arch/powerpc/include/asm/reg.h@@ -415,6 +415,7 @@ #define HFSCR_DSCR __MASK(FSCR_DSCR_LG) #define HFSCR_VECVSX __MASK(FSCR_VECVSX_LG) #define HFSCR_FP __MASK(FSCR_FP_LG) +#define HFSCR_INTR_CAUSE (ASM_CONST(0xFF) << 56) /* interrupt cause */ #define SPRN_TAR 0x32f /* Target Address Register */ #define SPRN_LPCR 0x13E /* LPAR Control Register */ #define LPCR_VPM0 ASM_CONST(0x8000000000000000)diff --git a/arch/powerpc/kvm/book3s_hv_nested.c b/arch/powerpc/kvm/book3s_hv_nested.c index 7656cb3..7b1088a 100644 --- a/arch/powerpc/kvm/book3s_hv_nested.c +++ b/arch/powerpc/kvm/book3s_hv_nested.c@@ -86,6 +86,22 @@ static void save_hv_return_state(struct kvm_vcpu *vcpu, int trap, } } +static void sanitise_hv_regs(struct kvm_vcpu *vcpu, struct hv_guest_state *hr) +{ + /* + * Don't let L1 enable features for L2 which we've disabled for L1, + * but preserve the interrupt cause field. + */ + hr->hfscr &= (HFSCR_INTR_CAUSE | vcpu->arch.hfscr); + + /* Don't let data address watchpoint match in hypervisor state */ + hr->dawrx0 &= ~DAWRX_HYP; + + /* Don't let completed instruction address breakpt match in HV state */ + if ((hr->ciabr & CIABR_PRIV) == CIABR_PRIV_HYPER) + hr->ciabr &= ~CIABR_PRIV; +} + static void restore_hv_regs(struct kvm_vcpu *vcpu, struct hv_guest_state *hr) { struct kvmppc_vcore *vc = vcpu->arch.vcore;@@ -198,6 +214,7 @@ long kvmhv_enter_nested_guest(struct kvm_vcpu *vcpu) mask = LPCR_DPFD | LPCR_ILE | LPCR_TC | LPCR_AIL | LPCR_LD | LPCR_LPES | LPCR_MER; lpcr = (vc->lpcr & ~mask) | (l2_hv.lpcr & mask); + sanitise_hv_regs(vcpu, &l2_hv); restore_hv_regs(vcpu, &l2_hv); vcpu->arch.ret = RESUME_GUEST;
-- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson
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