If max leaf is greater than 0xd but xsave not available to the guest, then the
current XSAVE size should not be filled in. This is a latent bug for now as
the guest max leaf is 0xd, but will become problematic in the future.
The comment concerning XSS state is wrong. VT-x doesn't manage host/guest
state automatically, but there is provision for "host only" bits to be set, so
the implications are still accurate.
Introduce {xstate,hw}_compressed_size() helpers to mirror the uncompressed
ones.
Signed-off-by: Andrew Cooper <andrew.coop...@citrix.com>
---
CC: Jan Beulich <jbeul...@suse.com>
CC: Roger Pau Monné <roger....@citrix.com>
CC: Wei Liu <w...@xen.org>
---
xen/arch/x86/cpuid.c | 23 +++++++--------------
xen/arch/x86/xstate.c | 49 ++++++++++++++++++++++++++++++++++++++++++++
xen/include/asm-x86/xstate.h | 1 +
3 files changed, 57 insertions(+), 16 deletions(-)
diff --git a/xen/arch/x86/cpuid.c b/xen/arch/x86/cpuid.c
index c7f8388e5d..92745aa63f 100644
--- a/xen/arch/x86/cpuid.c
+++ b/xen/arch/x86/cpuid.c
@@ -1041,24 +1041,15 @@ void guest_cpuid(const struct vcpu *v, uint32_t leaf,
case XSTATE_CPUID:
switch ( subleaf )
{
+ case 0:
+ if ( p->basic.xsave )
+ res->b = xstate_uncompressed_size(v->arch.xcr0);
+ break;
+
case 1:
if ( p->xstate.xsaves )
- {
- /*
- * TODO: Figure out what to do for XSS state. VT-x manages
- * host vs guest MSR_XSS automatically, so as soon as we start
- * supporting any XSS states, the wrong XSS will be in
- * context.
- */
- BUILD_BUG_ON(XSTATE_XSAVES_ONLY != 0);
-
- /*
- * Read CPUID[0xD,0/1].EBX from hardware. They vary with
- * enabled XSTATE, and appropraite XCR0|XSS are in context.
- */
- case 0:
- res->b = cpuid_count_ebx(leaf, subleaf);
- }
+ res->b = xstate_compressed_size(v->arch.xcr0 |
+ v->arch.msrs->xss.raw);
break;
}
break;
diff --git a/xen/arch/x86/xstate.c b/xen/arch/x86/xstate.c
index d4c01da574..03489f0cf4 100644
--- a/xen/arch/x86/xstate.c
+++ b/xen/arch/x86/xstate.c
@@ -602,6 +602,55 @@ unsigned int xstate_uncompressed_size(uint64_t xcr0)
return size;
}
+static unsigned int hw_compressed_size(uint64_t xstates)
+{
+ uint64_t curr_xcr0 = get_xcr0(), curr_xss = get_msr_xss();
+ unsigned int size;
+ bool ok;
+
+ ok = set_xcr0(xstates & ~XSTATE_XSAVES_ONLY);
+ ASSERT(ok);
+ set_msr_xss(xstates & XSTATE_XSAVES_ONLY);
+
+ size = cpuid_count_ebx(XSTATE_CPUID, 1);
+
+ ok = set_xcr0(curr_xcr0);
+ ASSERT(ok);
+ set_msr_xss(curr_xss);
+
+ return size;
+}
+
+unsigned int xstate_compressed_size(uint64_t xstates)
+{
+ unsigned int i, size = XSTATE_AREA_MIN_SIZE;
+
+ xstates &= ~XSTATE_FP_SSE;
+ for_each_set_bit ( i, &xstates, 63 )
+ {
+ if ( test_bit(i, &xstate_align) )
+ size = ROUNDUP(size, 64);
+
+ size += xstate_sizes[i];
+ }
+
+ /* In debug builds, cross-check our calculation with hardware. */
+ if ( IS_ENABLED(CONFIG_DEBUG) )
+ {
+ unsigned int hwsize;
+
+ xstates |= XSTATE_FP_SSE;
+ hwsize = hw_compressed_size(xstates);
+
+ if ( size != hwsize )
+ printk_once(XENLOG_ERR "%s(%#"PRIx64") size %#x != hwsize %#x\n",
+ __func__, xstates, size, hwsize);
+ size = hwsize;
+ }
+
+ return size;
+}
+
/* Collect the information of processor's extended state */
void xstate_init(struct cpuinfo_x86 *c)
{
diff --git a/xen/include/asm-x86/xstate.h b/xen/include/asm-x86/xstate.h
index 02d6f171b8..ecf7bbc5cd 100644
--- a/xen/include/asm-x86/xstate.h
+++ b/xen/include/asm-x86/xstate.h
@@ -108,6 +108,7 @@ void xstate_free_save_area(struct vcpu *v);
int xstate_alloc_save_area(struct vcpu *v);
void xstate_init(struct cpuinfo_x86 *c);
unsigned int xstate_uncompressed_size(uint64_t xcr0);
+unsigned int xstate_compressed_size(uint64_t states);
static inline uint64_t xgetbv(unsigned int index)
{
--
2.11.0
