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[PATCH v3 01/26] kvm: Merge kvm_check_extension() and kvm_vm_check_exten
From: |
Jean-Philippe Brucker |
Subject: |
[PATCH v3 01/26] kvm: Merge kvm_check_extension() and kvm_vm_check_extension() |
Date: |
Mon, 25 Nov 2024 19:56:00 +0000 |
The KVM_CHECK_EXTENSION ioctl can be issued either on the global fd
(/dev/kvm), or on the VM fd obtained with KVM_CREATE_VM. For most
extensions, KVM returns the same value with either method, but for some
of them it can refine the returned value depending on the VM type. The
KVM documentation [1] advises to use the VM fd:
Based on their initialization different VMs may have different
capabilities. It is thus encouraged to use the vm ioctl to query for
capabilities (available with KVM_CAP_CHECK_EXTENSION_VM on the vm fd)
Ongoing work on Arm confidential VMs confirms this, as some capabilities
become unavailable to confidential VMs, requiring changes in QEMU to use
kvm_vm_check_extension() instead of kvm_check_extension() [2]. Rather
than changing each check one by one, change kvm_check_extension() to
always issue the ioctl on the VM fd when available, and remove
kvm_vm_check_extension().
Fall back to the global fd when the VM check is unavailable:
* Ancient kernels do not support KVM_CHECK_EXTENSION on the VM fd, since
it was added by commit 92b591a4c46b ("KVM: Allow KVM_CHECK_EXTENSION
on the vm fd") in Linux 3.17 [3]. Support for Linux 3.16 ended in June
2020, but there may still be old images around.
* A couple of calls must be issued before the VM fd is available, since
they determine the VM type: KVM_CAP_MIPS_VZ and KVM_CAP_ARM_VM_IPA_SIZE
Does any user actually depend on the check being done on the global fd
instead of the VM fd? I surveyed all cases where KVM presently returns
different values depending on the query method. Luckily QEMU already
calls kvm_vm_check_extension() for most of those. Only three of them are
ambiguous, because currently done on the global fd:
* KVM_CAP_MAX_VCPUS and KVM_CAP_MAX_VCPU_ID on Arm, changes value if the
user requests a vGIC different from the default. But QEMU queries this
before vGIC configuration, so the reported value will be the same.
* KVM_CAP_SW_TLB on PPC. When issued on the global fd, returns false if
the kvm-hv module is loaded; when issued on the VM fd, returns false
only if the VM type is HV instead of PR. If this returns false, then
QEMU will fail to initialize a BOOKE206 MMU model.
So this patch supposedly improves things, as it allows to run this
type of vCPU even when both KVM modules are loaded.
* KVM_CAP_PPC_SECURE_GUEST. Similarly, doing this check on a VM fd
refines the returned value, and ensures that SVM is actually
supported. Since QEMU follows the check with kvm_vm_enable_cap(), this
patch should only provide better error reporting.
[1] https://www.kernel.org/doc/html/latest/virt/kvm/api.html#kvm-check-extension
[2] https://lore.kernel.org/kvm/875ybi0ytc.fsf@redhat.com/
[3] https://github.com/torvalds/linux/commit/92b591a4c46b
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Daniel Henrique Barboza <danielhb413@gmail.com>
Cc: qemu-ppc@nongnu.org
Suggested-by: Cornelia Huck <cohuck@redhat.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
---
include/sysemu/kvm.h | 2 --
include/sysemu/kvm_int.h | 1 +
accel/kvm/kvm-all.c | 41 +++++++++++++++++++---------------------
target/arm/kvm.c | 2 +-
target/i386/kvm/kvm.c | 6 +++---
target/ppc/kvm.c | 36 +++++++++++++++++------------------
6 files changed, 42 insertions(+), 46 deletions(-)
diff --git a/include/sysemu/kvm.h b/include/sysemu/kvm.h
index c3a60b2890..63c96d0096 100644
--- a/include/sysemu/kvm.h
+++ b/include/sysemu/kvm.h
@@ -437,8 +437,6 @@ bool kvm_arch_stop_on_emulation_error(CPUState *cpu);
int kvm_check_extension(KVMState *s, unsigned int extension);
-int kvm_vm_check_extension(KVMState *s, unsigned int extension);
-
#define kvm_vm_enable_cap(s, capability, cap_flags, ...) \
({ \
struct kvm_enable_cap cap = { \
diff --git a/include/sysemu/kvm_int.h b/include/sysemu/kvm_int.h
index a1e72763da..cb38085d54 100644
--- a/include/sysemu/kvm_int.h
+++ b/include/sysemu/kvm_int.h
@@ -166,6 +166,7 @@ struct KVMState
uint16_t xen_gnttab_max_frames;
uint16_t xen_evtchn_max_pirq;
char *device;
+ bool check_extension_vm;
};
void kvm_memory_listener_register(KVMState *s, KVMMemoryListener *kml,
diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 801cff16a5..7ea016d598 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -1238,7 +1238,11 @@ int kvm_check_extension(KVMState *s, unsigned int
extension)
{
int ret;
- ret = kvm_ioctl(s, KVM_CHECK_EXTENSION, extension);
+ if (!s->check_extension_vm) {
+ ret = kvm_ioctl(s, KVM_CHECK_EXTENSION, extension);
+ } else {
+ ret = kvm_vm_ioctl(s, KVM_CHECK_EXTENSION, extension);
+ }
if (ret < 0) {
ret = 0;
}
@@ -1246,19 +1250,6 @@ int kvm_check_extension(KVMState *s, unsigned int
extension)
return ret;
}
-int kvm_vm_check_extension(KVMState *s, unsigned int extension)
-{
- int ret;
-
- ret = kvm_vm_ioctl(s, KVM_CHECK_EXTENSION, extension);
- if (ret < 0) {
- /* VM wide version not implemented, use global one instead */
- ret = kvm_check_extension(s, extension);
- }
-
- return ret;
-}
-
/*
* We track the poisoned pages to be able to:
* - replace them on VM reset
@@ -1622,10 +1613,10 @@ static int kvm_dirty_ring_init(KVMState *s)
* Read the max supported pages. Fall back to dirty logging mode
* if the dirty ring isn't supported.
*/
- ret = kvm_vm_check_extension(s, capability);
+ ret = kvm_check_extension(s, capability);
if (ret <= 0) {
capability = KVM_CAP_DIRTY_LOG_RING_ACQ_REL;
- ret = kvm_vm_check_extension(s, capability);
+ ret = kvm_check_extension(s, capability);
}
if (ret <= 0) {
@@ -1648,7 +1639,7 @@ static int kvm_dirty_ring_init(KVMState *s)
}
/* Enable the backup bitmap if it is supported */
- ret = kvm_vm_check_extension(s, KVM_CAP_DIRTY_LOG_RING_WITH_BITMAP);
+ ret = kvm_check_extension(s, KVM_CAP_DIRTY_LOG_RING_WITH_BITMAP);
if (ret > 0) {
ret = kvm_vm_enable_cap(s, KVM_CAP_DIRTY_LOG_RING_WITH_BITMAP, 0);
if (ret) {
@@ -2404,7 +2395,7 @@ static void kvm_irqchip_create(KVMState *s)
*/
static int kvm_recommended_vcpus(KVMState *s)
{
- int ret = kvm_vm_check_extension(s, KVM_CAP_NR_VCPUS);
+ int ret = kvm_check_extension(s, KVM_CAP_NR_VCPUS);
return (ret) ? ret : 4;
}
@@ -2625,7 +2616,12 @@ static int kvm_init(MachineState *ms)
s->vmfd = ret;
- s->nr_as = kvm_vm_check_extension(s, KVM_CAP_MULTI_ADDRESS_SPACE);
+ ret = kvm_vm_ioctl(s, KVM_CHECK_EXTENSION, KVM_CAP_CHECK_EXTENSION_VM);
+ if (ret > 0) {
+ s->check_extension_vm = true;
+ }
+
+ s->nr_as = kvm_check_extension(s, KVM_CAP_MULTI_ADDRESS_SPACE);
if (s->nr_as <= 1) {
s->nr_as = 1;
}
@@ -2683,7 +2679,7 @@ static int kvm_init(MachineState *ms)
}
kvm_readonly_mem_allowed =
- (kvm_vm_check_extension(s, KVM_CAP_READONLY_MEM) > 0);
+ (kvm_check_extension(s, KVM_CAP_READONLY_MEM) > 0);
kvm_resamplefds_allowed =
(kvm_check_extension(s, KVM_CAP_IRQFD_RESAMPLE) > 0);
@@ -2717,7 +2713,8 @@ static int kvm_init(MachineState *ms)
goto err;
}
- kvm_supported_memory_attributes = kvm_vm_check_extension(s,
KVM_CAP_MEMORY_ATTRIBUTES);
+ kvm_supported_memory_attributes =
+ kvm_check_extension(s, KVM_CAP_MEMORY_ATTRIBUTES);
kvm_guest_memfd_supported =
kvm_check_extension(s, KVM_CAP_GUEST_MEMFD) &&
kvm_check_extension(s, KVM_CAP_USER_MEMORY2) &&
@@ -2743,7 +2740,7 @@ static int kvm_init(MachineState *ms)
memory_listener_register(&kvm_io_listener,
&address_space_io);
- s->sync_mmu = !!kvm_vm_check_extension(kvm_state, KVM_CAP_SYNC_MMU);
+ s->sync_mmu = !!kvm_check_extension(kvm_state, KVM_CAP_SYNC_MMU);
if (!s->sync_mmu) {
ret = ram_block_discard_disable(true);
assert(!ret);
diff --git a/target/arm/kvm.c b/target/arm/kvm.c
index 7b6812c0de..8bdf4abeb6 100644
--- a/target/arm/kvm.c
+++ b/target/arm/kvm.c
@@ -601,7 +601,7 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
if (s->kvm_eager_split_size) {
uint32_t sizes;
- sizes = kvm_vm_check_extension(s, KVM_CAP_ARM_SUPPORTED_BLOCK_SIZES);
+ sizes = kvm_check_extension(s, KVM_CAP_ARM_SUPPORTED_BLOCK_SIZES);
if (!sizes) {
s->kvm_eager_split_size = 0;
warn_report("Eager Page Split support not available");
diff --git a/target/i386/kvm/kvm.c b/target/i386/kvm/kvm.c
index 8e17942c3b..2f35e7468c 100644
--- a/target/i386/kvm/kvm.c
+++ b/target/i386/kvm/kvm.c
@@ -244,7 +244,7 @@ bool kvm_enable_hypercall(uint64_t enable_mask)
bool kvm_has_smm(void)
{
- return kvm_vm_check_extension(kvm_state, KVM_CAP_X86_SMM);
+ return kvm_check_extension(kvm_state, KVM_CAP_X86_SMM);
}
bool kvm_has_adjust_clock_stable(void)
@@ -3320,7 +3320,7 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
}
}
- if (kvm_vm_check_extension(s, KVM_CAP_X86_USER_SPACE_MSR)) {
+ if (kvm_check_extension(s, KVM_CAP_X86_USER_SPACE_MSR)) {
ret = kvm_vm_enable_userspace_msr(s);
if (ret < 0) {
return ret;
@@ -5936,7 +5936,7 @@ static bool __kvm_enable_sgx_provisioning(KVMState *s)
{
int fd, ret;
- if (!kvm_vm_check_extension(s, KVM_CAP_SGX_ATTRIBUTE)) {
+ if (!kvm_check_extension(s, KVM_CAP_SGX_ATTRIBUTE)) {
return false;
}
diff --git a/target/ppc/kvm.c b/target/ppc/kvm.c
index 3efc28f18b..8bcb0368ce 100644
--- a/target/ppc/kvm.c
+++ b/target/ppc/kvm.c
@@ -110,7 +110,7 @@ static uint32_t debug_inst_opcode;
static bool kvmppc_is_pr(KVMState *ks)
{
/* Assume KVM-PR if the GET_PVINFO capability is available */
- return kvm_vm_check_extension(ks, KVM_CAP_PPC_GET_PVINFO) != 0;
+ return kvm_check_extension(ks, KVM_CAP_PPC_GET_PVINFO) != 0;
}
static int kvm_ppc_register_host_cpu_type(void);
@@ -127,11 +127,11 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
cap_interrupt_unset = kvm_check_extension(s, KVM_CAP_PPC_UNSET_IRQ);
cap_segstate = kvm_check_extension(s, KVM_CAP_PPC_SEGSTATE);
cap_booke_sregs = kvm_check_extension(s, KVM_CAP_PPC_BOOKE_SREGS);
- cap_ppc_smt_possible = kvm_vm_check_extension(s, KVM_CAP_PPC_SMT_POSSIBLE);
+ cap_ppc_smt_possible = kvm_check_extension(s, KVM_CAP_PPC_SMT_POSSIBLE);
cap_spapr_tce = kvm_check_extension(s, KVM_CAP_SPAPR_TCE);
cap_spapr_tce_64 = kvm_check_extension(s, KVM_CAP_SPAPR_TCE_64);
cap_spapr_multitce = kvm_check_extension(s, KVM_CAP_SPAPR_MULTITCE);
- cap_spapr_vfio = kvm_vm_check_extension(s, KVM_CAP_SPAPR_TCE_VFIO);
+ cap_spapr_vfio = kvm_check_extension(s, KVM_CAP_SPAPR_TCE_VFIO);
cap_one_reg = kvm_check_extension(s, KVM_CAP_ONE_REG);
cap_hior = kvm_check_extension(s, KVM_CAP_PPC_HIOR);
cap_epr = kvm_check_extension(s, KVM_CAP_PPC_EPR);
@@ -140,23 +140,23 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
* Note: we don't set cap_papr here, because this capability is
* only activated after this by kvmppc_set_papr()
*/
- cap_htab_fd = kvm_vm_check_extension(s, KVM_CAP_PPC_HTAB_FD);
+ cap_htab_fd = kvm_check_extension(s, KVM_CAP_PPC_HTAB_FD);
cap_fixup_hcalls = kvm_check_extension(s, KVM_CAP_PPC_FIXUP_HCALL);
- cap_ppc_smt = kvm_vm_check_extension(s, KVM_CAP_PPC_SMT);
- cap_htm = kvm_vm_check_extension(s, KVM_CAP_PPC_HTM);
- cap_mmu_radix = kvm_vm_check_extension(s, KVM_CAP_PPC_MMU_RADIX);
- cap_mmu_hash_v3 = kvm_vm_check_extension(s, KVM_CAP_PPC_MMU_HASH_V3);
- cap_xive = kvm_vm_check_extension(s, KVM_CAP_PPC_IRQ_XIVE);
- cap_resize_hpt = kvm_vm_check_extension(s, KVM_CAP_SPAPR_RESIZE_HPT);
+ cap_ppc_smt = kvm_check_extension(s, KVM_CAP_PPC_SMT);
+ cap_htm = kvm_check_extension(s, KVM_CAP_PPC_HTM);
+ cap_mmu_radix = kvm_check_extension(s, KVM_CAP_PPC_MMU_RADIX);
+ cap_mmu_hash_v3 = kvm_check_extension(s, KVM_CAP_PPC_MMU_HASH_V3);
+ cap_xive = kvm_check_extension(s, KVM_CAP_PPC_IRQ_XIVE);
+ cap_resize_hpt = kvm_check_extension(s, KVM_CAP_SPAPR_RESIZE_HPT);
kvmppc_get_cpu_characteristics(s);
- cap_ppc_nested_kvm_hv = kvm_vm_check_extension(s, KVM_CAP_PPC_NESTED_HV);
+ cap_ppc_nested_kvm_hv = kvm_check_extension(s, KVM_CAP_PPC_NESTED_HV);
cap_large_decr = kvmppc_get_dec_bits();
- cap_fwnmi = kvm_vm_check_extension(s, KVM_CAP_PPC_FWNMI);
+ cap_fwnmi = kvm_check_extension(s, KVM_CAP_PPC_FWNMI);
/*
* Note: setting it to false because there is not such capability
* in KVM at this moment.
*
- * TODO: call kvm_vm_check_extension() with the right capability
+ * TODO: call kvm_check_extension() with the right capability
* after the kernel starts implementing it.
*/
cap_ppc_pvr_compat = false;
@@ -166,8 +166,8 @@ int kvm_arch_init(MachineState *ms, KVMState *s)
exit(1);
}
- cap_rpt_invalidate = kvm_vm_check_extension(s, KVM_CAP_PPC_RPT_INVALIDATE);
- cap_ail_mode_3 = kvm_vm_check_extension(s, KVM_CAP_PPC_AIL_MODE_3);
+ cap_rpt_invalidate = kvm_check_extension(s, KVM_CAP_PPC_RPT_INVALIDATE);
+ cap_ail_mode_3 = kvm_check_extension(s, KVM_CAP_PPC_AIL_MODE_3);
kvm_ppc_register_host_cpu_type();
return 0;
@@ -1976,7 +1976,7 @@ static int kvmppc_get_pvinfo(CPUPPCState *env, struct
kvm_ppc_pvinfo *pvinfo)
{
CPUState *cs = env_cpu(env);
- if (kvm_vm_check_extension(cs->kvm_state, KVM_CAP_PPC_GET_PVINFO) &&
+ if (kvm_check_extension(cs->kvm_state, KVM_CAP_PPC_GET_PVINFO) &&
!kvm_vm_ioctl(cs->kvm_state, KVM_PPC_GET_PVINFO, pvinfo)) {
return 0;
}
@@ -2298,7 +2298,7 @@ int kvmppc_reset_htab(int shift_hint)
/* Full emulation, tell caller to allocate htab itself */
return 0;
}
- if (kvm_vm_check_extension(kvm_state, KVM_CAP_PPC_ALLOC_HTAB)) {
+ if (kvm_check_extension(kvm_state, KVM_CAP_PPC_ALLOC_HTAB)) {
int ret;
ret = kvm_vm_ioctl(kvm_state, KVM_PPC_ALLOCATE_HTAB, &shift);
if (ret == -ENOTTY) {
@@ -2507,7 +2507,7 @@ static void kvmppc_get_cpu_characteristics(KVMState *s)
cap_ppc_safe_bounds_check = 0;
cap_ppc_safe_indirect_branch = 0;
- ret = kvm_vm_check_extension(s, KVM_CAP_PPC_GET_CPU_CHAR);
+ ret = kvm_check_extension(s, KVM_CAP_PPC_GET_CPU_CHAR);
if (!ret) {
return;
}
--
2.47.0
- [PATCH v3 01/26] kvm: Merge kvm_check_extension() and kvm_vm_check_extension(),
Jean-Philippe Brucker <=