| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-Id: <20240217014513.7853-4-dongli.zhang@oracle.com>
Date: Fri, 16 Feb 2024 17:45:13 -0800
From: Dongli Zhang <dongli.zhang@...cle.com>
To: kvm@...r.kernel.org
Cc: seanjc@...gle.com, pbonzini@...hat.com, linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] KVM: VMX: simplify MSR interception enable/disable
Currently, the is_valid_passthrough_msr() is only called by two sites:
vmx_enable_intercept_for_msr() and vmx_disable_intercept_for_msr(). The
is_valid_passthrough_msr() is called for two reasons.
1. Do WARN() if the input msr is neither x2APIC/PT/LBR passthrough MSRs,
nor the possible passthrough MSRs.
2. Return if the msr is a possible passthrough MSR.
While the is_valid_passthrough_msr() may traverse the
vmx_possible_passthrough_msrs[], the following
possible_passthrough_msr_slot() may traverse the save array again. There
is no need to call possible_passthrough_msr_slot() twice.
vmx_disable_intercept_for_msr()
-> is_valid_passthrough_msr()
-> possible_passthrough_msr_slot()
-> possible_passthrough_msr_slot()
Therefore, we merge the is_valid_passthrough_msr() and the following
possible_passthrough_msr_slot() into the same function:
- If the msr is not any passthrough MSR, WARN and return -ENOENT.
- Return VMX_OTHER_PASSTHROUGH if x2apic/PT/LBR.
- Return VMX_POSSIBLE_PASSTHROUGH and set possible_idx, if possible
passthrough MSRs.
Signed-off-by: Dongli Zhang <dongli.zhang@...cle.com>
---
arch/x86/kvm/vmx/vmx.c | 55 +++++++++++++++++++++---------------------
1 file changed, 28 insertions(+), 27 deletions(-)
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 5a866d3c2bc8..76dff0e7d8bd 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -669,14 +669,18 @@ static int possible_passthrough_msr_slot(u32 msr)
return -ENOENT;
}
-static bool is_valid_passthrough_msr(u32 msr)
+#define VMX_POSSIBLE_PASSTHROUGH 1
+#define VMX_OTHER_PASSTHROUGH 2
+/*
+ * Vefify if the msr is the passthrough MSRs.
+ * Return the index in *possible_idx if it is a possible passthrough MSR.
+ */
+static int validate_passthrough_msr(u32 msr, int *possible_idx)
{
- bool r;
-
switch (msr) {
case 0x800 ... 0x8ff:
/* x2APIC MSRs. These are handled in vmx_update_msr_bitmap_x2apic() */
- return true;
+ return VMX_OTHER_PASSTHROUGH;
case MSR_IA32_RTIT_STATUS:
case MSR_IA32_RTIT_OUTPUT_BASE:
case MSR_IA32_RTIT_OUTPUT_MASK:
@@ -691,14 +695,17 @@ static bool is_valid_passthrough_msr(u32 msr)
case MSR_LBR_CORE_FROM ... MSR_LBR_CORE_FROM + 8:
case MSR_LBR_CORE_TO ... MSR_LBR_CORE_TO + 8:
/* LBR MSRs. These are handled in vmx_update_intercept_for_lbr_msrs() */
- return true;
+ return VMX_OTHER_PASSTHROUGH;
}
- r = possible_passthrough_msr_slot(msr) != -ENOENT;
+ *possible_idx = possible_passthrough_msr_slot(msr);
+ WARN(*possible_idx == -ENOENT,
+ "Invalid MSR %x, please adapt vmx_possible_passthrough_msrs[]", msr);
- WARN(!r, "Invalid MSR %x, please adapt vmx_possible_passthrough_msrs[]", msr);
+ if (*possible_idx >= 0)
+ return VMX_POSSIBLE_PASSTHROUGH;
- return r;
+ return -ENOENT;
}
struct vmx_uret_msr *vmx_find_uret_msr(struct vcpu_vmx *vmx, u32 msr)
@@ -3954,6 +3961,7 @@ void vmx_disable_intercept_for_msr(struct kvm_vcpu *vcpu, u32 msr, int type)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
unsigned long *msr_bitmap = vmx->vmcs01.msr_bitmap;
+ int idx;
if (!cpu_has_vmx_msr_bitmap())
return;
@@ -3963,16 +3971,12 @@ void vmx_disable_intercept_for_msr(struct kvm_vcpu *vcpu, u32 msr, int type)
/*
* Mark the desired intercept state in shadow bitmap, this is needed
* for resync when the MSR filters change.
- */
- if (is_valid_passthrough_msr(msr)) {
- int idx = possible_passthrough_msr_slot(msr);
-
- if (idx != -ENOENT) {
- if (type & MSR_TYPE_R)
- clear_bit(idx, vmx->shadow_msr_intercept.read);
- if (type & MSR_TYPE_W)
- clear_bit(idx, vmx->shadow_msr_intercept.write);
- }
+ */
+ if (validate_passthrough_msr(msr, &idx) == VMX_POSSIBLE_PASSTHROUGH) {
+ if (type & MSR_TYPE_R)
+ clear_bit(idx, vmx->shadow_msr_intercept.read);
+ if (type & MSR_TYPE_W)
+ clear_bit(idx, vmx->shadow_msr_intercept.write);
}
if ((type & MSR_TYPE_R) &&
@@ -3998,6 +4002,7 @@ void vmx_enable_intercept_for_msr(struct kvm_vcpu *vcpu, u32 msr, int type)
{
struct vcpu_vmx *vmx = to_vmx(vcpu);
unsigned long *msr_bitmap = vmx->vmcs01.msr_bitmap;
+ int idx;
if (!cpu_has_vmx_msr_bitmap())
return;
@@ -4008,15 +4013,11 @@ void vmx_enable_intercept_for_msr(struct kvm_vcpu *vcpu, u32 msr, int type)
* Mark the desired intercept state in shadow bitmap, this is needed
* for resync when the MSR filter changes.
*/
- if (is_valid_passthrough_msr(msr)) {
- int idx = possible_passthrough_msr_slot(msr);
-
- if (idx != -ENOENT) {
- if (type & MSR_TYPE_R)
- set_bit(idx, vmx->shadow_msr_intercept.read);
- if (type & MSR_TYPE_W)
- set_bit(idx, vmx->shadow_msr_intercept.write);
- }
+ if (validate_passthrough_msr(msr, &idx) == VMX_POSSIBLE_PASSTHROUGH) {
+ if (type & MSR_TYPE_R)
+ set_bit(idx, vmx->shadow_msr_intercept.read);
+ if (type & MSR_TYPE_W)
+ set_bit(idx, vmx->shadow_msr_intercept.write);
}
if (type & MSR_TYPE_R)
--
2.34.1
Powered by blists - more mailing lists