[Xen-changelog] [xen staging] x86: make PV hypercall entry points work with !CONFIG_PV

[p***@xen.org]

commit 02cd41698504c25849394ba4a5e1a2f722cbd4e7
Author: Wei Liu <***@citrix.com>
AuthorDate: Fri Nov 2 13:44:01 2018 +0000
Commit: Wei Liu <***@citrix.com>
CommitDate: Thu Nov 8 16:40:20 2018 +0000

x86: make PV hypercall entry points work with !CONFIG_PV

We want Xen to crash if we hit these paths when PV is disabled.

For syscall, we provide stubs for {l,c}star_enter which end up calling
panic. For sysenter, we initialise CS to 0 so that #GP can be raised.

Signed-off-by: Wei Liu <***@citrix.com>
Reviewed-by: Andrew Cooper <***@citrix.com>
---
xen/arch/x86/hvm/vmx/vmcs.c | 5 +++--
xen/arch/x86/x86_64/traps.c | 19 +++++++++++++++++--
2 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index d9747b4fd3..dec21d1fa4 100644
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -1160,8 +1160,9 @@ static int construct_vmcs(struct vcpu *v)
__vmwrite(HOST_RIP, (unsigned long)vmx_asm_vmexit_handler);

/* Host SYSENTER CS:RIP. */
- __vmwrite(HOST_SYSENTER_CS, __HYPERVISOR_CS);
- __vmwrite(HOST_SYSENTER_EIP, (unsigned long)sysenter_entry);
+ __vmwrite(HOST_SYSENTER_CS, IS_ENABLED(CONFIG_PV) ? __HYPERVISOR_CS : 0);
+ __vmwrite(HOST_SYSENTER_EIP,
+ IS_ENABLED(CONFIG_PV) ? (unsigned long)sysenter_entry : 0);

/* MSR intercepts. */
__vmwrite(VM_EXIT_MSR_LOAD_COUNT, 0);
diff --git a/xen/arch/x86/x86_64/traps.c b/xen/arch/x86/x86_64/traps.c
index 27154f2ae2..4d506e2c18 100644
--- a/xen/arch/x86/x86_64/traps.c
+++ b/xen/arch/x86/x86_64/traps.c
@@ -298,8 +298,21 @@ static unsigned int write_stub_trampoline(
}

DEFINE_PER_CPU(struct stubs, stubs);
+
+#ifdef CONFIG_PV
void lstar_enter(void);
void cstar_enter(void);
+#else
+static inline void lstar_enter(void)
+{
+ panic("%s called\n", __func__);
+}
+
+static inline void cstar_enter(void)
+{
+ panic("%s called\n", __func__);
+}
+#endif /* CONFIG_PV */

void subarch_percpu_traps_init(void)
{
@@ -329,8 +342,10 @@ void subarch_percpu_traps_init(void)
{
/* SYSENTER entry. */
wrmsrl(MSR_IA32_SYSENTER_ESP, stack_bottom);
- wrmsrl(MSR_IA32_SYSENTER_EIP, (unsigned long)sysenter_entry);
- wrmsr(MSR_IA32_SYSENTER_CS, __HYPERVISOR_CS, 0);
+ wrmsrl(MSR_IA32_SYSENTER_EIP,
+ IS_ENABLED(CONFIG_PV) ? (unsigned long)sysenter_entry : 0);
+ wrmsr(MSR_IA32_SYSENTER_CS,
+ IS_ENABLED(CONFIG_PV) ? __HYPERVISOR_CS : 0, 0);
}

/* Trampoline for SYSCALL entry from compatibility mode. */
--
generated by git-patchbot for /home/xen/git/xen.git#staging