| Message ID | 20200227172306.21426-3-mgamal@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | KVM: Support guest MAXPHYADDR < host MAXPHYADDR | expand |
On Thu, Feb 27, 2020 at 9:23 AM Mohammed Gamal <mgamal@redhat.com> wrote: > > Check guest physical address against it's maximum physical memory. If Nit: "its," without an apostrophe. > the guest's physical address exceeds the maximum (i.e. has reserved bits > set), inject a guest page fault with PFERR_RSVD_MASK. > > Signed-off-by: Mohammed Gamal <mgamal@redhat.com> > --- > arch/x86/kvm/vmx/vmx.c | 13 +++++++++++++ > 1 file changed, 13 insertions(+) > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index 63aaf44edd1f..477d196aa235 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -5162,6 +5162,12 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu) > gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS); > trace_kvm_page_fault(gpa, exit_qualification); > > + /* Check if guest gpa doesn't exceed physical memory limits */ > + if (gpa >= (1ull << cpuid_maxphyaddr(vcpu))) { > + kvm_inject_rsvd_bits_pf(vcpu, gpa); Even if PFERR_RSVD_MASK is set in the page fault error code, shouldn't we set still conditionally set: PFERR_WRITE_MASK - for an attempted write PFERR_USER_MASK - for a usermode access PFERR_FETCH_MASK - for an instruction fetch > + return 1; > + } > + > /* Is it a read fault? */ > error_code = (exit_qualification & EPT_VIOLATION_ACC_READ) > ? PFERR_USER_MASK : 0; > @@ -5193,6 +5199,13 @@ static int handle_ept_misconfig(struct kvm_vcpu *vcpu) > * nGPA here instead of the required GPA. > */ > gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS); > + > + /* Check if guest gpa doesn't exceed physical memory limits */ > + if (gpa >= (1ull << cpuid_maxphyaddr(vcpu))) { > + kvm_inject_rsvd_bits_pf(vcpu, gpa); And here as well? > + return 1; > + } > + > if (!is_guest_mode(vcpu) && > !kvm_io_bus_write(vcpu, KVM_FAST_MMIO_BUS, gpa, 0, NULL)) { > trace_kvm_fast_mmio(gpa); > -- > 2.21.1 >
On Thu, Feb 27, 2020 at 09:55:32AM -0800, Jim Mattson wrote: > On Thu, Feb 27, 2020 at 9:23 AM Mohammed Gamal <mgamal@redhat.com> wrote: > > > > Check guest physical address against it's maximum physical memory. If > Nit: "its," without an apostrophe. > > > the guest's physical address exceeds the maximum (i.e. has reserved bits > > set), inject a guest page fault with PFERR_RSVD_MASK. Wish I had actually read this series when it first flew by, just spent several hours debugging this exact thing when running the "access" test. > > Signed-off-by: Mohammed Gamal <mgamal@redhat.com> > > --- > > arch/x86/kvm/vmx/vmx.c | 13 +++++++++++++ > > 1 file changed, 13 insertions(+) > > > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > > index 63aaf44edd1f..477d196aa235 100644 > > --- a/arch/x86/kvm/vmx/vmx.c > > +++ b/arch/x86/kvm/vmx/vmx.c > > @@ -5162,6 +5162,12 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu) > > gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS); > > trace_kvm_page_fault(gpa, exit_qualification); > > > > + /* Check if guest gpa doesn't exceed physical memory limits */ > > + if (gpa >= (1ull << cpuid_maxphyaddr(vcpu))) { Add a helper for this, it's easier than copy-pasting the comment and code everywhere. BIT_ULL() is also handy. static inline bool kvm_mmu_is_illegal_gpa(gpa_t gpa) { return (gpa < BIT_ULL(cpuid_maxphyaddr(vcpu))); } > > + kvm_inject_rsvd_bits_pf(vcpu, gpa); > > Even if PFERR_RSVD_MASK is set in the page fault error code, shouldn't > we set still conditionally set: > PFERR_WRITE_MASK - for an attempted write > PFERR_USER_MASK - for a usermode access > PFERR_FETCH_MASK - for an instruction fetch Yep. Move this down below where error_code is calculated. Then the code should be something like this. Not fun to handle this with EPT :-( Note, VMCS.GUEST_LINEAR_ADDRESS isn't guaranteed to be accurate, e.g. if the guest is putting bad gpas into Intel PT, but I don't think we have any choice but to blindly cram it in and hope for the best. if (unlikely(kvm_mmu_is_illegal_gpa(vcpu, gpa))) { /* Morph the EPT error code into a #PF error code. */ error_code &= ~(PFERR_USER_MASK | PFERR_GUEST_FINAL_MASK | PFERR_GUEST_PAGE_MASK); if (vmx_get_cpl(vcpu) == 3) error_code |= PFERR_USER_MASK; error_code |= PFERR_PRESENT_MASK; kvm_inject_rsvd_bits_pf(vcpu, vmcs_readl(GUEST_LINEAR_ADDRESS), error_code); return 1; } > > + return 1; > > + } > > + > > /* Is it a read fault? */ > > error_code = (exit_qualification & EPT_VIOLATION_ACC_READ) > > ? PFERR_USER_MASK : 0; > > @@ -5193,6 +5199,13 @@ static int handle_ept_misconfig(struct kvm_vcpu *vcpu) > > * nGPA here instead of the required GPA. > > */ > > gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS); > > + > > + /* Check if guest gpa doesn't exceed physical memory limits */ > > + if (gpa >= (1ull << cpuid_maxphyaddr(vcpu))) { > > + kvm_inject_rsvd_bits_pf(vcpu, gpa); > > And here as well? This shouldn't happen. If KVM creates a bad EPTE for an illegal GPA, we done goofed up. I.e. if (WARN_ON_ONCE(kvm_mmu_is_illegal_gpa(vcpu, gpa))) { vcpu->run->blah = blah; return 0; } > > > + return 1; > > + } > > + > > if (!is_guest_mode(vcpu) && > > !kvm_io_bus_write(vcpu, KVM_FAST_MMIO_BUS, gpa, 0, NULL)) { > > trace_kvm_fast_mmio(gpa); > > -- > > 2.21.1 > >
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index 63aaf44edd1f..477d196aa235 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -5162,6 +5162,12 @@ static int handle_ept_violation(struct kvm_vcpu *vcpu) gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS); trace_kvm_page_fault(gpa, exit_qualification); + /* Check if guest gpa doesn't exceed physical memory limits */ + if (gpa >= (1ull << cpuid_maxphyaddr(vcpu))) { + kvm_inject_rsvd_bits_pf(vcpu, gpa); + return 1; + } + /* Is it a read fault? */ error_code = (exit_qualification & EPT_VIOLATION_ACC_READ) ? PFERR_USER_MASK : 0; @@ -5193,6 +5199,13 @@ static int handle_ept_misconfig(struct kvm_vcpu *vcpu) * nGPA here instead of the required GPA. */ gpa = vmcs_read64(GUEST_PHYSICAL_ADDRESS); + + /* Check if guest gpa doesn't exceed physical memory limits */ + if (gpa >= (1ull << cpuid_maxphyaddr(vcpu))) { + kvm_inject_rsvd_bits_pf(vcpu, gpa); + return 1; + } + if (!is_guest_mode(vcpu) && !kvm_io_bus_write(vcpu, KVM_FAST_MMIO_BUS, gpa, 0, NULL)) { trace_kvm_fast_mmio(gpa);
Check guest physical address against it's maximum physical memory. If the guest's physical address exceeds the maximum (i.e. has reserved bits set), inject a guest page fault with PFERR_RSVD_MASK. Signed-off-by: Mohammed Gamal <mgamal@redhat.com> --- arch/x86/kvm/vmx/vmx.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)