[PATCH v5 03/28] x86/fpu/xstate: Modify address finders to handle both static and dynamic buffers

From: Chang S. Bae
Date: Sun May 23 2021 - 15:38:57 EST

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Have all the functions finding xstate address take a struct fpu * pointer
in preparation for dynamic state buffer support.

init_fpstate is a special case, which is indicated by a null pointer
parameter to get_xsave_addr() and __raw_xsave_addr().

No functional change.

Signed-off-by: Chang S. Bae <chang.seok.bae@xxxxxxxxx>
Reviewed-by: Len Brown <len.brown@xxxxxxxxx>
Cc: x86@xxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: kvm@xxxxxxxxxxxxxxx
---
Changes from v3:
* Updated the changelog. (Borislav Petkov)
* Updated the function comment to use kernel-doc style. (Borislav Petkov)

Changes from v2:
* Updated the changelog with task->fpu removed. (Borislav Petkov)

Changes from v1:
* Rebased on the upstream kernel (5.10)
---
arch/x86/include/asm/fpu/internal.h | 2 +-
arch/x86/include/asm/fpu/xstate.h | 2 +-
arch/x86/include/asm/pgtable.h | 2 +-
arch/x86/kernel/cpu/common.c | 2 +-
arch/x86/kernel/fpu/xstate.c | 46 ++++++++++++++++++++++-------
arch/x86/kvm/x86.c | 10 +++----
arch/x86/mm/pkeys.c | 2 +-
7 files changed, 44 insertions(+), 22 deletions(-)

diff --git a/arch/x86/include/asm/fpu/internal.h b/arch/x86/include/asm/fpu/internal.h
index d81d8c407dc0..0153c4d4ca77 100644
--- a/arch/x86/include/asm/fpu/internal.h
+++ b/arch/x86/include/asm/fpu/internal.h
@@ -579,7 +579,7 @@ static inline void switch_fpu_finish(struct fpu *new_fpu)
* return to userland e.g. for a copy_to_user() operation.
*/
if (current->mm) {
- pk = get_xsave_addr(&new_fpu->state.xsave, XFEATURE_PKRU);
+ pk = get_xsave_addr(new_fpu, XFEATURE_PKRU);
if (pk)
pkru_val = pk->pkru;
}
diff --git a/arch/x86/include/asm/fpu/xstate.h b/arch/x86/include/asm/fpu/xstate.h
index e0f1b22f53ce..24bf8d3f559a 100644
--- a/arch/x86/include/asm/fpu/xstate.h
+++ b/arch/x86/include/asm/fpu/xstate.h
@@ -100,7 +100,7 @@ extern u64 xstate_fx_sw_bytes[USER_XSTATE_FX_SW_WORDS];
extern void __init update_regset_xstate_info(unsigned int size,
u64 xstate_mask);

-void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr);
+void *get_xsave_addr(struct fpu *fpu, int xfeature_nr);
const void *get_xsave_field_ptr(int xfeature_nr);
int using_compacted_format(void);
int xfeature_size(int xfeature_nr);
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index b1099f2d9800..024699f19f96 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -141,7 +141,7 @@ static inline void write_pkru(u32 pkru)
if (!boot_cpu_has(X86_FEATURE_OSPKE))
return;

- pk = get_xsave_addr(&current->thread.fpu.state.xsave, XFEATURE_PKRU);
+ pk = get_xsave_addr(&current->thread.fpu, XFEATURE_PKRU);

/*
* The PKRU value in xstate needs to be in sync with the value that is
diff --git a/arch/x86/kernel/cpu/common.c b/arch/x86/kernel/cpu/common.c
index a1b756c49a93..0a6bd4e2c098 100644
--- a/arch/x86/kernel/cpu/common.c
+++ b/arch/x86/kernel/cpu/common.c
@@ -477,7 +477,7 @@ static __always_inline void setup_pku(struct cpuinfo_x86 *c)
return;

cr4_set_bits(X86_CR4_PKE);
- pk = get_xsave_addr(&init_fpstate.xsave, XFEATURE_PKRU);
+ pk = get_xsave_addr(NULL, XFEATURE_PKRU);
if (pk)
pk->pkru = init_pkru_value;
/*
diff --git a/arch/x86/kernel/fpu/xstate.c b/arch/x86/kernel/fpu/xstate.c
index cb634c6afbb2..b55771eb739f 100644
--- a/arch/x86/kernel/fpu/xstate.c
+++ b/arch/x86/kernel/fpu/xstate.c
@@ -890,19 +890,34 @@ void fpu__resume_cpu(void)
}
}

-/*
+/**
+ * __raw_xsave_addr() - Find the address where the feature state is saved.
+ *
* Given an xstate feature nr, calculate where in the xsave
* buffer the state is. Callers should ensure that the buffer
* is valid.
+ *
+ * If @fpu is NULL, use init_fpstate.
+ *
+ * @fpu: A struct fpu * pointer
+ *
+ * Return: An address of the feature state in the buffer
*/
-static void *__raw_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
+static void *__raw_xsave_addr(struct fpu *fpu, int xfeature_nr)
{
+ void *xsave;
+
if (!xfeature_enabled(xfeature_nr)) {
WARN_ON_FPU(1);
return NULL;
}

- return (void *)xsave + xstate_comp_offsets[xfeature_nr];
+ if (fpu)
+ xsave = &fpu->state.xsave;
+ else
+ xsave = &init_fpstate.xsave;
+
+ return xsave + xstate_comp_offsets[xfeature_nr];
}
/*
* Given the xsave area and a state inside, this function returns the
@@ -915,15 +930,18 @@ static void *__raw_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
* this will return NULL.
*
* Inputs:
- * xstate: the thread's storage area for all FPU data
+ * fpu: the thread's FPU data to reference xstate buffer(s).
+ * (A null pointer parameter indicates init_fpstate.)
* xfeature_nr: state which is defined in xsave.h (e.g. XFEATURE_FP,
* XFEATURE_SSE, etc...)
* Output:
* address of the state in the xsave area, or NULL if the
* field is not present in the xsave buffer.
*/
-void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
+void *get_xsave_addr(struct fpu *fpu, int xfeature_nr)
{
+ struct xregs_state *xsave;
+
/*
* Do we even *have* xsave state?
*/
@@ -936,6 +954,12 @@ void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
*/
WARN_ONCE(!(xfeatures_mask_all & BIT_ULL(xfeature_nr)),
"get of unsupported state");
+
+ if (fpu)
+ xsave = &fpu->state.xsave;
+ else
+ xsave = &init_fpstate.xsave;
+
/*
* This assumes the last 'xsave*' instruction to
* have requested that 'xfeature_nr' be saved.
@@ -950,7 +974,7 @@ void *get_xsave_addr(struct xregs_state *xsave, int xfeature_nr)
if (!(xsave->header.xfeatures & BIT_ULL(xfeature_nr)))
return NULL;

- return __raw_xsave_addr(xsave, xfeature_nr);
+ return __raw_xsave_addr(fpu, xfeature_nr);
}
EXPORT_SYMBOL_GPL(get_xsave_addr);

@@ -981,7 +1005,7 @@ const void *get_xsave_field_ptr(int xfeature_nr)
*/
fpu__save(fpu);

- return get_xsave_addr(&fpu->state.xsave, xfeature_nr);
+ return get_xsave_addr(fpu, xfeature_nr);
}

#ifdef CONFIG_ARCH_HAS_PKEYS
@@ -1116,7 +1140,7 @@ void copy_xstate_to_kernel(struct membuf to, struct fpu *fpu)
* Copy only in-use xstates:
*/
if ((header.xfeatures >> i) & 1) {
- void *src = __raw_xsave_addr(xsave, i);
+ void *src = __raw_xsave_addr(fpu, i);

copy_part(&to, &last, xstate_offsets[i],
xstate_sizes[i], src);
@@ -1151,7 +1175,7 @@ int copy_kernel_to_xstate(struct fpu *fpu, const void *kbuf)
u64 mask = ((u64)1 << i);

if (hdr.xfeatures & mask) {
- void *dst = __raw_xsave_addr(xsave, i);
+ void *dst = __raw_xsave_addr(fpu, i);

offset = xstate_offsets[i];
size = xstate_sizes[i];
@@ -1208,7 +1232,7 @@ int copy_user_to_xstate(struct fpu *fpu, const void __user *ubuf)
u64 mask = ((u64)1 << i);

if (hdr.xfeatures & mask) {
- void *dst = __raw_xsave_addr(xsave, i);
+ void *dst = __raw_xsave_addr(fpu, i);

offset = xstate_offsets[i];
size = xstate_sizes[i];
@@ -1450,7 +1474,7 @@ void update_pasid(void)
*/
xsave = &fpu->state.xsave;
xsave->header.xfeatures |= XFEATURE_MASK_PASID;
- ppasid_state = get_xsave_addr(xsave, XFEATURE_PASID);
+ ppasid_state = get_xsave_addr(fpu, XFEATURE_PASID);
/*
* Since XFEATURE_MASK_PASID is set in xfeatures, ppasid_state
* won't be NULL and no need to check its value.
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 9af0a3c52b62..01c8642cb56c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -4589,7 +4589,7 @@ static void fill_xsave(u8 *dest, struct kvm_vcpu *vcpu)
while (valid) {
u64 xfeature_mask = valid & -valid;
int xfeature_nr = fls64(xfeature_mask) - 1;
- void *src = get_xsave_addr(xsave, xfeature_nr);
+ void *src = get_xsave_addr(vcpu->arch.guest_fpu, xfeature_nr);

if (src) {
u32 size, offset, ecx, edx;
@@ -4632,7 +4632,7 @@ static void load_xsave(struct kvm_vcpu *vcpu, u8 *src)
while (valid) {
u64 xfeature_mask = valid & -valid;
int xfeature_nr = fls64(xfeature_mask) - 1;
- void *dest = get_xsave_addr(xsave, xfeature_nr);
+ void *dest = get_xsave_addr(vcpu->arch.guest_fpu, xfeature_nr);

if (dest) {
u32 size, offset, ecx, edx;
@@ -10473,12 +10473,10 @@ void kvm_vcpu_reset(struct kvm_vcpu *vcpu, bool init_event)
*/
if (init_event)
kvm_put_guest_fpu(vcpu);
- mpx_state_buffer = get_xsave_addr(&vcpu->arch.guest_fpu->state.xsave,
- XFEATURE_BNDREGS);
+ mpx_state_buffer = get_xsave_addr(vcpu->arch.guest_fpu, XFEATURE_BNDREGS);
if (mpx_state_buffer)
memset(mpx_state_buffer, 0, sizeof(struct mpx_bndreg_state));
- mpx_state_buffer = get_xsave_addr(&vcpu->arch.guest_fpu->state.xsave,
- XFEATURE_BNDCSR);
+ mpx_state_buffer = get_xsave_addr(vcpu->arch.guest_fpu, XFEATURE_BNDCSR);
if (mpx_state_buffer)
memset(mpx_state_buffer, 0, sizeof(struct mpx_bndcsr));
if (init_event)
diff --git a/arch/x86/mm/pkeys.c b/arch/x86/mm/pkeys.c
index a2332eef66e9..5f2609af4223 100644
--- a/arch/x86/mm/pkeys.c
+++ b/arch/x86/mm/pkeys.c
@@ -177,7 +177,7 @@ static ssize_t init_pkru_write_file(struct file *file,
return -EINVAL;

WRITE_ONCE(init_pkru_value, new_init_pkru);
- pk = get_xsave_addr(&init_fpstate.xsave, XFEATURE_PKRU);
+ pk = get_xsave_addr(NULL, XFEATURE_PKRU);
if (!pk)
return -EINVAL;
pk->pkru = new_init_pkru;
--
2.17.1

Next message: Chang S. Bae: "[PATCH v5 16/28] x86/fpu/xstate: Support ptracer-induced xstate buffer expansion"
Previous message: Chang S. Bae: "[PATCH v5 28/28] x86/fpu/amx: Clear the AMX state when appropriate"
In reply to: Andy Lutomirski: "Re: [PATCH v5 28/28] x86/fpu/amx: Clear the AMX state when appropriate"
Next in thread: Chang S. Bae: "[PATCH v5 16/28] x86/fpu/xstate: Support ptracer-induced xstate buffer expansion"
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