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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v5 5/7] xen/x86: disable global pages for domains with XPTI active
Instead of flushing the TLB from global pages when switching address
spaces with XPTI being active just disable global pages via %cr4
completely when a domain subject to XPTI is active. This avoids the
need for extra TLB flushes as loading %cr3 will remove all TLB
entries.
In order to avoid states with cr3/cr4 having inconsistent values
(e.g. global pages being activated while cr3 already specifies a XPTI
address space) move loading of the new cr4 value to write_ptbase()
(actually to write_cr3_cr4() called by write_ptbase()).
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
V4:
- don't use mmu_cr4_features for setting new cr4 value (Jan Beulich)
- use simpler scheme for setting X86_CR4_PGE in
pv_guest_cr4_to_real_cr4() (Jan Beulich)
V3:
- move cr4 loading for all domains from *_ctxt_switch_to() to
write_cr3_cr4() called by write_ptbase() (Jan Beulich)
- rebase
---
xen/arch/x86/domain.c | 5 -----
xen/arch/x86/flushtlb.c | 13 ++++++++-----
xen/arch/x86/mm.c | 14 +++++++++++---
xen/arch/x86/x86_64/entry.S | 10 ----------
xen/common/efi/runtime.c | 4 ++--
xen/include/asm-x86/domain.h | 3 ++-
xen/include/asm-x86/flushtlb.h | 2 +-
7 files changed, 24 insertions(+), 27 deletions(-)
diff --git a/xen/arch/x86/domain.c b/xen/arch/x86/domain.c
index 9c229594f4..c2bb70c483 100644
--- a/xen/arch/x86/domain.c
+++ b/xen/arch/x86/domain.c
@@ -1522,17 +1522,12 @@ void paravirt_ctxt_switch_from(struct vcpu *v)
void paravirt_ctxt_switch_to(struct vcpu *v)
{
root_pgentry_t *root_pgt = this_cpu(root_pgt);
- unsigned long cr4;
if ( root_pgt )
root_pgt[root_table_offset(PERDOMAIN_VIRT_START)] =
l4e_from_page(v->domain->arch.perdomain_l3_pg,
__PAGE_HYPERVISOR_RW);
- cr4 = pv_guest_cr4_to_real_cr4(v);
- if ( unlikely(cr4 != read_cr4()) )
- write_cr4(cr4);
-
if ( unlikely(v->arch.debugreg[7] & DR7_ACTIVE_MASK) )
activate_debugregs(v);
diff --git a/xen/arch/x86/flushtlb.c b/xen/arch/x86/flushtlb.c
index f793b70696..5dcd9a2bf6 100644
--- a/xen/arch/x86/flushtlb.c
+++ b/xen/arch/x86/flushtlb.c
@@ -89,20 +89,23 @@ static void do_tlb_flush(void)
post_flush(t);
}
-void write_cr3(unsigned long cr3)
+void write_cr3_cr4(unsigned long cr3, unsigned long cr4)
{
- unsigned long flags, cr4;
+ unsigned long flags;
u32 t;
/* This non-reentrant function is sometimes called in interrupt context. */
local_irq_save(flags);
t = pre_flush();
- cr4 = read_cr4();
- write_cr4(cr4 & ~X86_CR4_PGE);
+ if ( read_cr4() & X86_CR4_PGE )
+ write_cr4(cr4 & ~X86_CR4_PGE);
+
asm volatile ( "mov %0, %%cr3" : : "r" (cr3) : "memory" );
- write_cr4(cr4);
+
+ if ( read_cr4() != cr4 )
+ write_cr4(cr4);
post_flush(t);
diff --git a/xen/arch/x86/mm.c b/xen/arch/x86/mm.c
index 131433af9b..55c437751f 100644
--- a/xen/arch/x86/mm.c
+++ b/xen/arch/x86/mm.c
@@ -506,20 +506,28 @@ void make_cr3(struct vcpu *v, mfn_t mfn)
void write_ptbase(struct vcpu *v)
{
struct cpu_info *cpu_info = get_cpu_info();
+ unsigned long new_cr4;
+
+ new_cr4 = (is_pv_vcpu(v) && !is_idle_vcpu(v))
+ ? pv_guest_cr4_to_real_cr4(v)
+ : ((read_cr4() & ~X86_CR4_TSD) | X86_CR4_PGE);
if ( is_pv_vcpu(v) && v->domain->arch.pv_domain.xpti )
{
cpu_info->root_pgt_changed = true;
cpu_info->pv_cr3 = __pa(this_cpu(root_pgt));
- asm volatile ( "mov %0, %%cr3" : : "r" (v->arch.cr3) : "memory" );
+ write_cr3_cr4(v->arch.cr3, new_cr4);
}
else
{
- /* Make sure to clear xen_cr3 before pv_cr3; write_cr3() serializes. */
+ /* Make sure to clear xen_cr3 before pv_cr3. */
cpu_info->xen_cr3 = 0;
- write_cr3(v->arch.cr3);
+ /* write_cr3_cr4() serializes. */
+ write_cr3_cr4(v->arch.cr3, new_cr4);
cpu_info->pv_cr3 = 0;
}
+
+ ASSERT(is_pv_vcpu(v) || read_cr4() == mmu_cr4_features);
}
/*
diff --git a/xen/arch/x86/x86_64/entry.S b/xen/arch/x86/x86_64/entry.S
index 5026cfa490..6298ed65cc 100644
--- a/xen/arch/x86/x86_64/entry.S
+++ b/xen/arch/x86/x86_64/entry.S
@@ -154,13 +154,8 @@ restore_all_guest:
ROOT_PAGETABLE_LAST_XEN_SLOT - 1) * 8, %rdi
rep movsq
.Lrag_copy_done:
- mov STACK_CPUINFO_FIELD(cr4)(%rdx), %rdi
mov %r9, STACK_CPUINFO_FIELD(xen_cr3)(%rdx)
- mov %rdi, %rsi
- and $~X86_CR4_PGE, %rdi
- mov %rdi, %cr4
mov %rax, %cr3
- mov %rsi, %cr4
.Lrag_keep_cr3:
/* Restore stashed SPEC_CTRL value. */
@@ -216,12 +211,7 @@ restore_all_xen:
* so "g" will have to do.
*/
UNLIKELY_START(g, exit_cr3)
- mov %cr4, %rdi
- mov %rdi, %rsi
- and $~X86_CR4_PGE, %rdi
- mov %rdi, %cr4
mov %rax, %cr3
- mov %rsi, %cr4
UNLIKELY_END(exit_cr3)
/* WARNING! `ret`, `call *`, `jmp *` not safe beyond this point. */
diff --git a/xen/common/efi/runtime.c b/xen/common/efi/runtime.c
index 3dbc2e8ee5..fad8ca9e95 100644
--- a/xen/common/efi/runtime.c
+++ b/xen/common/efi/runtime.c
@@ -111,7 +111,7 @@ struct efi_rs_state efi_rs_enter(void)
lgdt(&gdt_desc);
}
- write_cr3(virt_to_maddr(efi_l4_pgtable));
+ write_cr3_cr4(virt_to_maddr(efi_l4_pgtable), read_cr4());
return state;
}
@@ -120,7 +120,7 @@ void efi_rs_leave(struct efi_rs_state *state)
{
if ( !state->cr3 )
return;
- write_cr3(state->cr3);
+ write_cr3_cr4(state->cr3, read_cr4());
if ( is_pv_vcpu(current) && !is_idle_vcpu(current) )
{
struct desc_ptr gdt_desc = {
diff --git a/xen/include/asm-x86/domain.h b/xen/include/asm-x86/domain.h
index ed4199931a..b7894dc8c8 100644
--- a/xen/include/asm-x86/domain.h
+++ b/xen/include/asm-x86/domain.h
@@ -618,9 +618,10 @@ unsigned long pv_guest_cr4_fixup(const struct vcpu *,
unsigned long guest_cr4);
#define pv_guest_cr4_to_real_cr4(v) \
(((v)->arch.pv_vcpu.ctrlreg[4] \
| (mmu_cr4_features \
- & (X86_CR4_PGE | X86_CR4_PSE | X86_CR4_SMEP | \
+ & (X86_CR4_PSE | X86_CR4_SMEP | \
X86_CR4_SMAP | X86_CR4_OSXSAVE | \
X86_CR4_FSGSBASE)) \
+ | ((v)->domain->arch.pv_domain.xpti ? 0 : X86_CR4_PGE) \
| ((v)->domain->arch.vtsc ? X86_CR4_TSD : 0)) \
& ~X86_CR4_DE)
#define real_cr4_to_pv_guest_cr4(c) \
diff --git a/xen/include/asm-x86/flushtlb.h b/xen/include/asm-x86/flushtlb.h
index 052f0fa403..1eb9682de4 100644
--- a/xen/include/asm-x86/flushtlb.h
+++ b/xen/include/asm-x86/flushtlb.h
@@ -84,7 +84,7 @@ static inline unsigned long read_cr3(void)
}
/* Write pagetable base and implicitly tick the tlbflush clock. */
-void write_cr3(unsigned long cr3);
+void write_cr3_cr4(unsigned long cr3, unsigned long cr4);
/* flush_* flag fields: */
/*
--
2.13.6
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