[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v7 3/6] VMX: Make sure PI is in proper state before install the hooks
We may hit the last ASSERT() in vmx_vcpu_block in the current code, since vmx_vcpu_block() may get called before vmx_pi_switch_to() has been installed or executed. Here We use cmpxchg to update the NDST field, this can make sure we only update the NDST when vmx_pi_switch_to() has not been called. So the NDST is in a proper state in vmx_vcpu_block(). Suggested-by: Jan Beulich <JBeulich@xxxxxxxx> Signed-off-by: Feng Wu <feng.wu@xxxxxxxxx> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx> --- v6: - Comments changes - Define macro 'APIC_INVALID_DEST' for '0xffffffff' v5: - Use 0xffffffff as the invalid value for NDST field. v4: - This patch is previously called "Pause/Unpause the domain before/after assigning PI hooks" - Remove the pause/unpause method - Use cmpxchg to update NDST xen/arch/x86/hvm/vmx/vmcs.c | 13 +++++-------- xen/arch/x86/hvm/vmx/vmx.c | 27 ++++++++++++++++++++++++++- xen/include/asm-x86/hvm/vmx/vmx.h | 2 ++ 3 files changed, 33 insertions(+), 9 deletions(-) diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c index 1bd875a..e8e3616 100644 --- a/xen/arch/x86/hvm/vmx/vmcs.c +++ b/xen/arch/x86/hvm/vmx/vmcs.c @@ -956,16 +956,13 @@ void virtual_vmcs_vmwrite(const struct vcpu *v, u32 vmcs_encoding, u64 val) */ static void pi_desc_init(struct vcpu *v) { - uint32_t dest; - v->arch.hvm_vmx.pi_desc.nv = posted_intr_vector; - dest = cpu_physical_id(v->processor); - - if ( x2apic_enabled ) - v->arch.hvm_vmx.pi_desc.ndst = dest; - else - v->arch.hvm_vmx.pi_desc.ndst = MASK_INSR(dest, PI_xAPIC_NDST_MASK); + /* + * Mark NDST as invalid, then we can use this invalid value as a + * marker to whether update NDST or not in vmx_pi_hooks_assign(). + */ + v->arch.hvm_vmx.pi_desc.ndst = APIC_INVALID_DEST; } static int construct_vmcs(struct vcpu *v) diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c index 7e7bc8b..d70acec 100644 --- a/xen/arch/x86/hvm/vmx/vmx.c +++ b/xen/arch/x86/hvm/vmx/vmx.c @@ -206,14 +206,39 @@ static void vmx_pi_do_resume(struct vcpu *v) /* This function is called when pcidevs_lock is held */ void vmx_pi_hooks_assign(struct domain *d) { + struct vcpu *v; + if ( !iommu_intpost || !has_hvm_container_domain(d) ) return; ASSERT(!d->arch.hvm_domain.vmx.vcpu_block); - d->arch.hvm_domain.vmx.vcpu_block = vmx_vcpu_block; + /* + * We carefully handle the timing here: + * - Install the context switch first + * - Then set the NDST field + * - Install the block and resume hooks in the end + * + * This can make sure the PI (especially the NDST feild) is + * in proper state when we call vmx_vcpu_block(). + */ d->arch.hvm_domain.vmx.pi_switch_from = vmx_pi_switch_from; d->arch.hvm_domain.vmx.pi_switch_to = vmx_pi_switch_to; + + for_each_vcpu ( d, v ) + { + unsigned int dest = cpu_physical_id(v->processor); + struct pi_desc *pi_desc = &v->arch.hvm_vmx.pi_desc; + + /* + * We don't need to update NDST if vmx_pi_switch_to() + * has already got called. + */ + (void)cmpxchg(&pi_desc->ndst, APIC_INVALID_DEST, + x2apic_enabled ? dest : MASK_INSR(dest, PI_xAPIC_NDST_MASK)); + } + + d->arch.hvm_domain.vmx.vcpu_block = vmx_vcpu_block; d->arch.hvm_domain.vmx.pi_do_resume = vmx_pi_do_resume; } diff --git a/xen/include/asm-x86/hvm/vmx/vmx.h b/xen/include/asm-x86/hvm/vmx/vmx.h index 4cdd9b1..2f0435c 100644 --- a/xen/include/asm-x86/hvm/vmx/vmx.h +++ b/xen/include/asm-x86/hvm/vmx/vmx.h @@ -573,6 +573,8 @@ void vmx_pi_per_cpu_init(unsigned int cpu); void vmx_pi_hooks_assign(struct domain *d); void vmx_pi_hooks_deassign(struct domain *d); +#define APIC_INVALID_DEST 0xffffffff + /* EPT violation qualifications definitions */ #define _EPT_READ_VIOLATION 0 #define EPT_READ_VIOLATION (1UL<<_EPT_READ_VIOLATION) -- 2.1.0 _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx https://lists.xen.org/xen-devel
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