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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen staging] x86: Remove fpu_initialised/fpu_dirty
commit 4b9851c645220903fd996f997102fb63144fac4f
Author: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
AuthorDate: Tue Mar 24 18:19:35 2026 +0000
Commit: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Mon Mar 30 15:48:13 2026 +0100
x86: Remove fpu_initialised/fpu_dirty
With lazy FPU removed, fpu_initialised and fpu_dirty are always set to
true in vcpu_restore_fpu() so remove them and adjust the code
accordingly.
There is a small user-visible change here. After this commit, calling
XEN_DOMCTL_getvcpucontext immediately after vCPU creation would show the
FPU as initialized (with a clean state) whereas before it would show as
uninitialized.
Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
xen/arch/x86/domctl.c | 5 ++---
xen/arch/x86/hvm/emulate.c | 6 +-----
xen/arch/x86/hvm/hvm.c | 15 ++++++---------
xen/arch/x86/hvm/vlapic.c | 3 ---
xen/arch/x86/i387.c | 31 ++-----------------------------
xen/arch/x86/include/asm/hvm/hvm.h | 1 -
xen/arch/x86/include/asm/xstate.h | 11 -----------
xen/arch/x86/xstate.c | 21 +++++----------------
xen/common/domain.c | 2 --
xen/include/xen/sched.h | 4 ----
10 files changed, 16 insertions(+), 83 deletions(-)
diff --git a/xen/arch/x86/domctl.c b/xen/arch/x86/domctl.c
index 942f41c584..8d474b7623 100644
--- a/xen/arch/x86/domctl.c
+++ b/xen/arch/x86/domctl.c
@@ -1406,11 +1406,10 @@ void arch_get_info_guest(struct vcpu *v,
vcpu_guest_context_u c)
VCPU_UNMAP_XSAVE_AREA(v, xsave_area);
if ( is_pv_domain(d) )
- c(flags = v->arch.pv.vgc_flags & ~(VGCF_i387_valid|VGCF_in_kernel));
+ c(flags = v->arch.pv.vgc_flags & ~VGCF_in_kernel);
else
c(flags = 0);
- if ( v->fpu_initialised )
- c(flags |= VGCF_i387_valid);
+ c(flags |= VGCF_i387_valid);
if ( !(v->pause_flags & VPF_down) )
c(flags |= VGCF_online);
if ( !compat )
diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index 2daea084f1..48c7320360 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -2517,9 +2517,7 @@ static int cf_check hvmemul_get_fpu(
{
struct vcpu *curr = current;
- if ( !curr->fpu_dirtied )
- alternative_vcall(hvm_funcs.fpu_dirty_intercept);
- else if ( type == X86EMUL_FPU_fpu )
+ if ( type == X86EMUL_FPU_fpu )
{
/* Has a fastpath for `current`, so there's no actual map */
const struct xsave_struct *xsave_area = VCPU_MAP_XSAVE_AREA(curr);
@@ -2537,8 +2535,6 @@ static int cf_check hvmemul_get_fpu(
* masking of all exceptions by FNSTENV.)
*/
save_fpu_enable();
- curr->fpu_initialised = true;
- curr->fpu_dirtied = true;
if ( (fpu_ctxt->fcw & 0x3f) != 0x3f )
{
uint16_t fcw;
diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index b62b058861..3edc2491e2 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -866,6 +866,7 @@ static int cf_check hvm_save_cpu_ctxt(struct vcpu *v,
hvm_domain_context_t *h)
.dr7 = v->arch.dr7,
.msr_efer = v->arch.hvm.guest_efer,
};
+ const struct xsave_struct *xsave_area;
/*
* We don't need to save state for a vcpu that is down; the restore
@@ -933,15 +934,11 @@ static int cf_check hvm_save_cpu_ctxt(struct vcpu *v,
hvm_domain_context_t *h)
ctxt.ldtr_base = seg.base;
ctxt.ldtr_arbytes = seg.attr;
- if ( v->fpu_initialised )
- {
- const struct xsave_struct *xsave_area = VCPU_MAP_XSAVE_AREA(v);
-
- BUILD_BUG_ON(sizeof(ctxt.fpu_regs) != sizeof(xsave_area->fpu_sse));
- memcpy(ctxt.fpu_regs, &xsave_area->fpu_sse, sizeof(ctxt.fpu_regs));
- VCPU_UNMAP_XSAVE_AREA(v, xsave_area);
- ctxt.flags = XEN_X86_FPU_INITIALISED;
- }
+ xsave_area = VCPU_MAP_XSAVE_AREA(v);
+ BUILD_BUG_ON(sizeof(ctxt.fpu_regs) != sizeof(xsave_area->fpu_sse));
+ memcpy(ctxt.fpu_regs, &xsave_area->fpu_sse, sizeof(ctxt.fpu_regs));
+ VCPU_UNMAP_XSAVE_AREA(v, xsave_area);
+ ctxt.flags = XEN_X86_FPU_INITIALISED;
return hvm_save_entry(CPU, v->vcpu_id, h, &ctxt);
}
diff --git a/xen/arch/x86/hvm/vlapic.c b/xen/arch/x86/hvm/vlapic.c
index 79697487ba..885f5d304b 100644
--- a/xen/arch/x86/hvm/vlapic.c
+++ b/xen/arch/x86/hvm/vlapic.c
@@ -276,7 +276,6 @@ static void vlapic_init_sipi_one(struct vcpu *target,
uint32_t icr)
switch ( icr & APIC_DM_MASK )
{
case APIC_DM_INIT: {
- bool fpu_initialised;
int rc;
/* No work on INIT de-assert for P4-type APIC. */
@@ -289,10 +288,8 @@ static void vlapic_init_sipi_one(struct vcpu *target,
uint32_t icr)
hvm_vcpu_down(target);
domain_lock(target->domain);
/* Reset necessary VCPU state. This does not include FPU state. */
- fpu_initialised = target->fpu_initialised;
rc = vcpu_reset(target);
ASSERT(!rc);
- target->fpu_initialised = fpu_initialised;
vlapic_do_init(vcpu_vlapic(target));
domain_unlock(target->domain);
break;
diff --git a/xen/arch/x86/i387.c b/xen/arch/x86/i387.c
index 88018397b1..5e893a2aab 100644
--- a/xen/arch/x86/i387.c
+++ b/xen/arch/x86/i387.c
@@ -110,22 +110,7 @@ static inline void fpu_fxrstor(struct vcpu *v)
static inline uint64_t vcpu_xsave_mask(const struct vcpu *v)
{
- if ( v->fpu_dirtied )
- return v->arch.nonlazy_xstate_used ? XSTATE_ALL : XSTATE_LAZY;
-
- ASSERT(v->arch.nonlazy_xstate_used);
-
- /*
- * The offsets of components which live in the extended region of
- * compact xsave area are not fixed. Xsave area may be overwritten
- * when a xsave with v->fpu_dirtied set is followed by one with
- * v->fpu_dirtied clear.
- * In such case, if hypervisor uses compact xsave area and guest
- * has ever used lazy states (checking xcr0_accum excluding
- * XSTATE_FP_SSE), vcpu_xsave_mask will return XSTATE_ALL. Otherwise
- * return XSTATE_NONLAZY.
- */
- return xstate_all(v) ? XSTATE_ALL : XSTATE_NONLAZY;
+ return v->arch.nonlazy_xstate_used ? XSTATE_ALL : XSTATE_LAZY;
}
/* Save x87 extended state */
@@ -201,19 +186,11 @@ void vcpu_restore_fpu(struct vcpu *v)
/* Avoid recursion */
clts();
- /*
- * When saving full state even with !v->fpu_dirtied (see vcpu_xsave_mask()
- * above) we also need to restore full state, to prevent subsequently
- * saving state belonging to another vCPU.
- */
if ( cpu_has_xsave )
fpu_xrstor(v, XSTATE_ALL);
else
fpu_fxrstor(v);
- v->fpu_initialised = 1;
- v->fpu_dirtied = 1;
-
/* Xen doesn't need TS set, but the guest might. */
if ( is_pv_vcpu(v) && (v->arch.pv.ctrlreg[0] & X86_CR0_TS) )
stts();
@@ -225,7 +202,7 @@ void vcpu_restore_fpu(struct vcpu *v)
*/
static bool _vcpu_save_fpu(struct vcpu *v)
{
- if ( !v->fpu_dirtied && !v->arch.nonlazy_xstate_used )
+ if ( !v->arch.nonlazy_xstate_used )
return false;
ASSERT(!is_idle_vcpu(v));
@@ -238,8 +215,6 @@ static bool _vcpu_save_fpu(struct vcpu *v)
else
fpu_fxsave(v);
- v->fpu_dirtied = 0;
-
return true;
}
@@ -265,7 +240,6 @@ void vcpu_reset_fpu(struct vcpu *v)
{
struct xsave_struct *xsave_area = VCPU_MAP_XSAVE_AREA(v);
- v->fpu_initialised = false;
*xsave_area = (struct xsave_struct) {
.xsave_hdr.xstate_bv = X86_XCR0_X87,
};
@@ -282,7 +256,6 @@ void vcpu_setup_fpu(struct vcpu *v, const void *data)
{
struct xsave_struct *xsave_area = VCPU_MAP_XSAVE_AREA(v);
- v->fpu_initialised = true;
*xsave_area = (struct xsave_struct) {
.fpu_sse = *(const fpusse_t*)data,
.xsave_hdr.xstate_bv = XSTATE_FP_SSE,
diff --git a/xen/arch/x86/include/asm/hvm/hvm.h
b/xen/arch/x86/include/asm/hvm/hvm.h
index a9425c8cff..846b91ebef 100644
--- a/xen/arch/x86/include/asm/hvm/hvm.h
+++ b/xen/arch/x86/include/asm/hvm/hvm.h
@@ -184,7 +184,6 @@ struct hvm_function_table {
/* Instruction intercepts: non-void return values are X86EMUL codes. */
void (*wbinvd_intercept)(void);
- void (*fpu_dirty_intercept)(void);
int (*msr_read_intercept)(unsigned int msr, uint64_t *msr_content);
int (*msr_write_intercept)(unsigned int msr, uint64_t msr_content);
void (*handle_cd)(struct vcpu *v, unsigned long value);
diff --git a/xen/arch/x86/include/asm/xstate.h
b/xen/arch/x86/include/asm/xstate.h
index e3b9745543..ca38c43ec1 100644
--- a/xen/arch/x86/include/asm/xstate.h
+++ b/xen/arch/x86/include/asm/xstate.h
@@ -132,17 +132,6 @@ xsave_area_compressed(const struct xsave_struct
*xsave_area)
return xsave_area->xsave_hdr.xcomp_bv & XSTATE_COMPACTION_ENABLED;
}
-static inline bool xstate_all(const struct vcpu *v)
-{
- /*
- * XSTATE_FP_SSE may be excluded, because the offsets of XSTATE_FP_SSE
- * (in the legacy region of xsave area) are fixed, so saving
- * XSTATE_FP_SSE will not cause overwriting problem with XSAVES/XSAVEC.
- */
- return xsave_area_compressed(v->arch.xsave_area) &&
- (v->arch.xcr0_accum & XSTATE_LAZY & ~XSTATE_FP_SSE);
-}
-
/*
* Fetch a pointer to a vCPU's XSAVE area
*
diff --git a/xen/arch/x86/xstate.c b/xen/arch/x86/xstate.c
index defe9b3f0c..c42cdc9462 100644
--- a/xen/arch/x86/xstate.c
+++ b/xen/arch/x86/xstate.c
@@ -1005,28 +1005,17 @@ int handle_xsetbv(u32 index, u64 new_bv)
if ( new_bv & XSTATE_NONLAZY )
curr->arch.nonlazy_xstate_used = 1;
- mask &= curr->fpu_dirtied ? ~XSTATE_FP_SSE : XSTATE_NONLAZY;
+ mask &= ~XSTATE_FP_SSE;
if ( mask )
{
unsigned long cr0 = read_cr0();
+ /* Has a fastpath for `current`, so there's no actual map */
+ struct xsave_struct *xsave_area = VCPU_MAP_XSAVE_AREA(curr);
clts();
- if ( curr->fpu_dirtied )
- {
- /* Has a fastpath for `current`, so there's no actual map */
- struct xsave_struct *xsave_area = VCPU_MAP_XSAVE_AREA(curr);
- asm ( "stmxcsr %0" : "=m" (xsave_area->fpu_sse.mxcsr) );
- VCPU_UNMAP_XSAVE_AREA(curr, xsave_area);
- }
- else if ( xstate_all(curr) )
- {
- /* See the comment in i387.c:vcpu_restore_fpu_eager(). */
- mask |= XSTATE_LAZY;
- curr->fpu_initialised = 1;
- curr->fpu_dirtied = 1;
- cr0 &= ~X86_CR0_TS;
- }
+ asm ( "stmxcsr %0" : "=m" (xsave_area->fpu_sse.mxcsr) );
+ VCPU_UNMAP_XSAVE_AREA(curr, xsave_area);
xrstor(curr, mask);
if ( cr0 & X86_CR0_TS )
write_cr0(cr0);
diff --git a/xen/common/domain.c b/xen/common/domain.c
index ab910fcf93..30cfea3045 100644
--- a/xen/common/domain.c
+++ b/xen/common/domain.c
@@ -1824,8 +1824,6 @@ int vcpu_reset(struct vcpu *v)
clear_bit(v->vcpu_id, d->poll_mask);
v->poll_evtchn = 0;
- v->fpu_initialised = 0;
- v->fpu_dirtied = 0;
v->is_initialised = 0;
if ( v->affinity_broken & VCPU_AFFINITY_OVERRIDE )
vcpu_temporary_affinity(v, NR_CPUS, VCPU_AFFINITY_OVERRIDE);
diff --git a/xen/include/xen/sched.h b/xen/include/xen/sched.h
index 40a35fc15c..212c7d765c 100644
--- a/xen/include/xen/sched.h
+++ b/xen/include/xen/sched.h
@@ -212,10 +212,6 @@ struct vcpu
struct guest_area runstate_guest_area;
unsigned int new_state;
- /* Has the FPU been initialised? */
- bool fpu_initialised;
- /* Has the FPU been used since it was last saved? */
- bool fpu_dirtied;
/* Initialization completed for this VCPU? */
bool is_initialised;
/* Currently running on a CPU? */
--
generated by git-patchbot for /home/xen/git/xen.git#staging
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