From 7d8cbbabcb1234ffba9a946083073a5e01cdc020 Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Wed, 13 May 2020 18:51:30 +0100 Subject: accel/tcg: Relax va restrictions on 64-bit guests MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit We cannot at present limit a 64-bit guest to a virtual address space smaller than the host. It will mostly work to ignore this limitation, except if the guest uses high bits of the address space for tags. But it will certainly work better, as presently we can wind up failing to allocate the guest stack. Widen our user-only page tree to the host or abi pointer width. Remove the workaround for this problem from target/alpha. Always validate guest addresses vs reserved_va, as there we control allocation ourselves. Signed-off-by: Richard Henderson Signed-off-by: Alex Bennée Message-Id: <20200513175134.19619-7-alex.bennee@linaro.org> --- accel/tcg/translate-all.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) (limited to 'accel') diff --git a/accel/tcg/translate-all.c b/accel/tcg/translate-all.c index 9924e66..e4f703a 100644 --- a/accel/tcg/translate-all.c +++ b/accel/tcg/translate-all.c @@ -173,8 +173,13 @@ struct page_collection { #define TB_FOR_EACH_JMP(head_tb, tb, n) \ TB_FOR_EACH_TAGGED((head_tb)->jmp_list_head, tb, n, jmp_list_next) -/* In system mode we want L1_MAP to be based on ram offsets, - while in user mode we want it to be based on virtual addresses. */ +/* + * In system mode we want L1_MAP to be based on ram offsets, + * while in user mode we want it to be based on virtual addresses. + * + * TODO: For user mode, see the caveat re host vs guest virtual + * address spaces near GUEST_ADDR_MAX. + */ #if !defined(CONFIG_USER_ONLY) #if HOST_LONG_BITS < TARGET_PHYS_ADDR_SPACE_BITS # define L1_MAP_ADDR_SPACE_BITS HOST_LONG_BITS @@ -182,7 +187,7 @@ struct page_collection { # define L1_MAP_ADDR_SPACE_BITS TARGET_PHYS_ADDR_SPACE_BITS #endif #else -# define L1_MAP_ADDR_SPACE_BITS TARGET_VIRT_ADDR_SPACE_BITS +# define L1_MAP_ADDR_SPACE_BITS MIN(HOST_LONG_BITS, TARGET_ABI_BITS) #endif /* Size of the L2 (and L3, etc) page tables. */ @@ -2497,9 +2502,7 @@ void page_set_flags(target_ulong start, target_ulong end, int flags) /* This function should never be called with addresses outside the guest address space. If this assert fires, it probably indicates a missing call to h2g_valid. */ -#if TARGET_ABI_BITS > L1_MAP_ADDR_SPACE_BITS - assert(end <= ((target_ulong)1 << L1_MAP_ADDR_SPACE_BITS)); -#endif + assert(end - 1 <= GUEST_ADDR_MAX); assert(start < end); assert_memory_lock(); -- cgit v1.1