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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v6 02/16] x86/hvm: remove multiple open coded 'chunking' loops
...in hvmemul_read/write()
Add hvmemul_phys_mmio_access() and hvmemul_linear_mmio_access() functions
to reduce code duplication.
NOTE: This patch also introduces a change in 'chunking' around a page
boundary. Previously (for example) an 8 byte access at the last
byte of a page would get carried out as 8 single-byte accesses.
It will now be carried out as a single-byte access, followed by
a 4-byte access, a 2-byte access and then another single-byte
access.
Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
Cc: Keir Fraser <keir@xxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
xen/arch/x86/hvm/emulate.c | 223 +++++++++++++++++++++++---------------------
1 file changed, 116 insertions(+), 107 deletions(-)
diff --git a/xen/arch/x86/hvm/emulate.c b/xen/arch/x86/hvm/emulate.c
index 8b60843..b823d84 100644
--- a/xen/arch/x86/hvm/emulate.c
+++ b/xen/arch/x86/hvm/emulate.c
@@ -539,6 +539,117 @@ static int hvmemul_virtual_to_linear(
return X86EMUL_EXCEPTION;
}
+static int hvmemul_phys_mmio_access(
+ paddr_t gpa, unsigned int size, uint8_t dir, uint8_t *buffer)
+{
+ unsigned long one_rep = 1;
+ unsigned int chunk;
+ int rc;
+
+ /* Accesses must fall within a page. */
+ BUG_ON((gpa & ~PAGE_MASK) + size > PAGE_SIZE);
+
+ /*
+ * hvmemul_do_io() cannot handle non-power-of-2 accesses or
+ * accesses larger than sizeof(long), so choose the highest power
+ * of 2 not exceeding sizeof(long) as the 'chunk' size.
+ */
+ ASSERT(size != 0);
+ chunk = 1u << (fls(size) - 1);
+ if ( chunk > sizeof (long) )
+ chunk = sizeof (long);
+
+ for ( ;; )
+ {
+ rc = hvmemul_do_mmio_buffer(gpa, &one_rep, chunk, dir, 0,
+ buffer);
+ if ( rc != X86EMUL_OKAY )
+ break;
+
+ /* Advance to the next chunk. */
+ gpa += chunk;
+ buffer += chunk;
+ size -= chunk;
+
+ if ( size == 0 )
+ break;
+
+ /*
+ * If the chunk now exceeds the remaining size, choose the next
+ * lowest power of 2 that will fit.
+ */
+ while ( chunk > size )
+ chunk >>= 1;
+ }
+
+ return rc;
+}
+
+static int hvmemul_linear_mmio_access(
+ unsigned long gla, unsigned int size, uint8_t dir, uint8_t *buffer,
+ uint32_t pfec, struct hvm_emulate_ctxt *hvmemul_ctxt, bool_t known_gpfn)
+{
+ struct hvm_vcpu_io *vio = ¤t->arch.hvm_vcpu.hvm_io;
+ unsigned long offset = gla & ~PAGE_MASK;
+ unsigned int chunk;
+ paddr_t gpa;
+ unsigned long one_rep = 1;
+ int rc;
+
+ chunk = min_t(unsigned int, size, PAGE_SIZE - offset);
+
+ if ( known_gpfn )
+ gpa = pfn_to_paddr(vio->mmio_gpfn) | offset;
+ else
+ {
+ rc = hvmemul_linear_to_phys(gla, &gpa, chunk, &one_rep, pfec,
+ hvmemul_ctxt);
+ if ( rc != X86EMUL_OKAY )
+ return rc;
+ }
+
+ for ( ;; )
+ {
+ rc = hvmemul_phys_mmio_access(gpa, chunk, dir, buffer);
+ if ( rc != X86EMUL_OKAY )
+ break;
+
+ gla += chunk;
+ buffer += chunk;
+ size -= chunk;
+
+ if ( size == 0 )
+ break;
+
+ ASSERT((gla & ~PAGE_MASK) == 0);
+ chunk = min_t(unsigned int, size, PAGE_SIZE);
+ rc = hvmemul_linear_to_phys(gla, &gpa, chunk, &one_rep, pfec,
+ hvmemul_ctxt);
+ if ( rc != X86EMUL_OKAY )
+ return rc;
+ }
+
+ return rc;
+}
+
+static inline int hvmemul_linear_mmio_read(
+ unsigned long gla, unsigned int size, void *buffer,
+ uint32_t pfec, struct hvm_emulate_ctxt *hvmemul_ctxt,
+ bool_t translate)
+{
+ return hvmemul_linear_mmio_access(gla, size, IOREQ_READ, buffer,
+ pfec, hvmemul_ctxt, translate);
+}
+
+static inline int hvmemul_linear_mmio_write(
+ unsigned long gla, unsigned int size, void *buffer,
+ uint32_t pfec, struct hvm_emulate_ctxt *hvmemul_ctxt,
+ bool_t translate)
+{
+ return hvmemul_linear_mmio_access(gla, size, IOREQ_WRITE, buffer,
+ pfec, hvmemul_ctxt, translate);
+}
+
static int __hvmemul_read(
enum x86_segment seg,
unsigned long offset,
@@ -549,51 +660,19 @@ static int __hvmemul_read(
{
struct vcpu *curr = current;
unsigned long addr, reps = 1;
- unsigned int off, chunk = min(bytes, 1U << LONG_BYTEORDER);
uint32_t pfec = PFEC_page_present;
struct hvm_vcpu_io *vio = &curr->arch.hvm_vcpu.hvm_io;
- paddr_t gpa;
int rc;
rc = hvmemul_virtual_to_linear(
seg, offset, bytes, &reps, access_type, hvmemul_ctxt, &addr);
if ( rc != X86EMUL_OKAY )
return rc;
- off = addr & (PAGE_SIZE - 1);
- /*
- * We only need to handle sizes actual instruction operands can have. All
- * such sizes are either powers of 2 or the sum of two powers of 2. Thus
- * picking as initial chunk size the largest power of 2 not greater than
- * the total size will always result in only power-of-2 size requests
- * issued to hvmemul_do_mmio() (hvmemul_do_io() rejects non-powers-of-2).
- */
- while ( chunk & (chunk - 1) )
- chunk &= chunk - 1;
- if ( off + bytes > PAGE_SIZE )
- while ( off & (chunk - 1) )
- chunk >>= 1;
-
if ( ((access_type != hvm_access_insn_fetch
? vio->mmio_access.read_access
: vio->mmio_access.insn_fetch)) &&
(vio->mmio_gva == (addr & PAGE_MASK)) )
- {
- gpa = (((paddr_t)vio->mmio_gpfn << PAGE_SHIFT) | off);
- while ( (off + chunk) <= PAGE_SIZE )
- {
- rc = hvmemul_do_mmio_buffer(gpa, &reps, chunk, IOREQ_READ, 0,
- p_data);
- if ( rc != X86EMUL_OKAY || bytes == chunk )
- return rc;
- addr += chunk;
- off += chunk;
- gpa += chunk;
- p_data += chunk;
- bytes -= chunk;
- if ( bytes < chunk )
- chunk = bytes;
- }
- }
+ return hvmemul_linear_mmio_read(addr, bytes, p_data, pfec,
hvmemul_ctxt, 1);
if ( (seg != x86_seg_none) &&
(hvmemul_ctxt->seg_reg[x86_seg_ss].attr.fields.dpl == 3) )
@@ -612,30 +691,8 @@ static int __hvmemul_read(
case HVMCOPY_bad_gfn_to_mfn:
if ( access_type == hvm_access_insn_fetch )
return X86EMUL_UNHANDLEABLE;
- rc = hvmemul_linear_to_phys(addr, &gpa, chunk, &reps, pfec,
- hvmemul_ctxt);
- while ( rc == X86EMUL_OKAY )
- {
- rc = hvmemul_do_mmio_buffer(gpa, &reps, chunk, IOREQ_READ, 0,
- p_data);
- if ( rc != X86EMUL_OKAY || bytes == chunk )
- break;
- addr += chunk;
- off += chunk;
- p_data += chunk;
- bytes -= chunk;
- if ( bytes < chunk )
- chunk = bytes;
- if ( off < PAGE_SIZE )
- gpa += chunk;
- else
- {
- rc = hvmemul_linear_to_phys(addr, &gpa, chunk, &reps, pfec,
- hvmemul_ctxt);
- off = 0;
- }
- }
- return rc;
+
+ return hvmemul_linear_mmio_read(addr, bytes, p_data, pfec,
hvmemul_ctxt, 0);
case HVMCOPY_gfn_paged_out:
case HVMCOPY_gfn_shared:
return X86EMUL_RETRY;
@@ -701,43 +758,18 @@ static int hvmemul_write(
container_of(ctxt, struct hvm_emulate_ctxt, ctxt);
struct vcpu *curr = current;
unsigned long addr, reps = 1;
- unsigned int off, chunk = min(bytes, 1U << LONG_BYTEORDER);
uint32_t pfec = PFEC_page_present | PFEC_write_access;
struct hvm_vcpu_io *vio = &curr->arch.hvm_vcpu.hvm_io;
- paddr_t gpa;
int rc;
rc = hvmemul_virtual_to_linear(
seg, offset, bytes, &reps, hvm_access_write, hvmemul_ctxt, &addr);
if ( rc != X86EMUL_OKAY )
return rc;
- off = addr & (PAGE_SIZE - 1);
- /* See the respective comment in __hvmemul_read(). */
- while ( chunk & (chunk - 1) )
- chunk &= chunk - 1;
- if ( off + bytes > PAGE_SIZE )
- while ( off & (chunk - 1) )
- chunk >>= 1;
if ( vio->mmio_access.write_access &&
(vio->mmio_gva == (addr & PAGE_MASK)) )
- {
- gpa = (((paddr_t)vio->mmio_gpfn << PAGE_SHIFT) | off);
- while ( (off + chunk) <= PAGE_SIZE )
- {
- rc = hvmemul_do_mmio_buffer(gpa, &reps, chunk, IOREQ_WRITE, 0,
- p_data);
- if ( rc != X86EMUL_OKAY || bytes == chunk )
- return rc;
- addr += chunk;
- off += chunk;
- gpa += chunk;
- p_data += chunk;
- bytes -= chunk;
- if ( bytes < chunk )
- chunk = bytes;
- }
- }
+ return hvmemul_linear_mmio_write(addr, bytes, p_data, pfec,
hvmemul_ctxt, 1);
if ( (seg != x86_seg_none) &&
(hvmemul_ctxt->seg_reg[x86_seg_ss].attr.fields.dpl == 3) )
@@ -752,30 +784,7 @@ static int hvmemul_write(
case HVMCOPY_bad_gva_to_gfn:
return X86EMUL_EXCEPTION;
case HVMCOPY_bad_gfn_to_mfn:
- rc = hvmemul_linear_to_phys(addr, &gpa, chunk, &reps, pfec,
- hvmemul_ctxt);
- while ( rc == X86EMUL_OKAY )
- {
- rc = hvmemul_do_mmio_buffer(gpa, &reps, chunk, IOREQ_WRITE, 0,
- p_data);
- if ( rc != X86EMUL_OKAY || bytes == chunk )
- break;
- addr += chunk;
- off += chunk;
- p_data += chunk;
- bytes -= chunk;
- if ( bytes < chunk )
- chunk = bytes;
- if ( off < PAGE_SIZE )
- gpa += chunk;
- else
- {
- rc = hvmemul_linear_to_phys(addr, &gpa, chunk, &reps, pfec,
- hvmemul_ctxt);
- off = 0;
- }
- }
- return rc;
+ return hvmemul_linear_mmio_write(addr, bytes, p_data, pfec,
hvmemul_ctxt, 0);
case HVMCOPY_gfn_paged_out:
case HVMCOPY_gfn_shared:
return X86EMUL_RETRY;
--
1.7.10.4
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